These are a list and review of the best sci fi films. It is not a full list as some of them are not worth watching.
Starting with films from the 2010s.
a rather surprisingly good science fiction film as it stars tom cruise. good effects and plot to keep you guessing and on the edge of your seat. enough action without being a typical tom cruise action film. well worth watching if you like sci fi films. a sort of post-apocalyptic story but with lots of future sci fi technology based above and on the earth.
entertaining enough but nothing special. a bit of future space sci fi technology and ideas. if you need to watch a science fiction film, have not seen this and there is nothing else better sci fi to watch then give it a go to get it off the list.
not sure if this is sci fi or not but it involves drama in space around the earth for some astronauts. a very different film as it has lots of quiet (sound) sections that represent the vacuum of space. you will either love it or think its a total waste of your time.
its like a reboot of snake plisken and escape from new york with the same sense of dark humour and action but involving a prison that is in a satellite orbit of earth. great action, decent story and gets the balance right of what it is trying to be. guy pearce is a surprise as the lead actor and carries it and the film all the way.
total recall (2012)
very different to the original 1990 version. comparing the 2 films is difficult as it does not set out to be a faithful remake. lots wrong with it but lots right also with sci fi technology and ideas. the most important thing about a remake of total recall is will you see a lady with 3 boobies?
this film surprised everyone. no one was expecting them to make a judge dredd film with this story line. some hated it but its literally pure dredd. violence, tech, dark, judge dredd, action, judge dredd humour. also it has judge dredd in it.
source code (2011)
a film that if you dont know anything about sneaks up on you and is a pleasant trip. a sort of sci fi groundhog day, so there is a lot of repeated storyline but they use it well. has the look and set up of the scenes (repeated locations) to be a small budget movie but turns out to have a budget of over 20 million!
Rise of The planet of the apes (2011)
reboot of the planet of the apes series after tim burtons disastrous attempt . it really delivers and develops the series as they go along. not science fiction technology or space stuff but sci fi.
tron: legacy (2010) and tron (1982)
get fucked up and enjoy the original as it still looks great, then watch the sequel. tron was truly groundbreaking and draw dropping in its day. now updated and tron legacy looks awesome and does well with the story.
fuck yeah! immense visuals and a story line that isnt dumbed down. if you love science fiction films that are not about space then you should love this film.
2000s science fiction films - earth based
surprisingly great film, full of action but with an unexpected story. based in the near future involving gaming, virtual reality worlds and guns. what more do you want?
district 9 (2009)
really good film, is it an alien invasion film though? based on earth but with aliens and alien tech to keep the geeks happy.
a scanner darkly (2006) based on the philip k dick book so you know its going to be weird and unusual. if you like odd films then this is for you.
i, robot (2004)
a future where robots help humans live and then it all goes wrong. good story for hollywood with a bit of mystery.
alien vs predator (2004)
if you love the individual alien or predator series of sci fi films then you should love this film when the aliens take on the predators and humans. complete hollywood action films, just sit back and enjoy.
1990s science fiction films
the matrix (1999)
utterly awesome film and series. the second one (the matrix reloaded) was the best of the trilogy. action, guns, nearly every line a memorable quote. the basic story line 'stolen' from previous films and books before it but the film transforms them into something special.
really good movie about genetic engineering and the pressure or desires of life and your expected role in it.
very different to other science fiction films, not about action, guns or aliens. tense thriller and puzzle film set in a simple idea. expands the brain. if you want something alternative without lots of hero man action then this is for you.
the lawnmower man (1992)
certainly ahead of the game for when it came out. who knows if you will love it or think its has dated or was rubbish even when it first came out. involves virtual reality, mind altering and enhancing drugs and a retard. all the ingredients needed for a sci fi film.
total recall (1990)
arnold schwarzenegger at his best in one of the best sci fi films of its time for effects and story. great eye popping fun the whole way through. involves mars, earth, aliens, mutants, arnie and ladies with 3 tits - what more do you want?
1980s sci fi films
the abyss (1989)
proper psychological scary film. do not watch unless in the company of others and during the day, even then be aware. or just be more of a man than us. we got surprised by this 'kids' film and mentally shat ourselves. maybe not scary for others or now but we were not expecting this. its not a horror film as such, just a sort of thriller involving a deep sea expedition.
they live (1988)
super awesome film about aliens on earth and control of humans. with one of the best and most realistic fight scenes ever. great lines and action all the way through. you will know if someone else has seen it as, even if they dont remember the name they will remember as soon as you describe it. most importantly of all obey and watch this film.
japanese anime film that is immense. how do you easily explain any anime film? just watch it and be in awe as it was done in 1988.
the start of the predator film series and its complete tension, action and arnold schwarzenegger versus a worthy opponent deep in the jungle.
you have 10 seconds to comply and watch this sci fi film where a cop is turned into a robocop.
the running man (1987)
the late 80s were arnies golden years and here is another classic idea for a film. the acting and sets may be dated now but it was great for its time. he is trapped into playing a deadly violent game where there is lots of violence and arnie and cheesy one liners. perfect combo.
the fly (1986)
an experiment goes wrong for a scientist and the fly is the result. be afraid. be very afraid.
if you need a good fun and very loose sort of sci fi 1980s film then you are gonna call on ghostbusters.
the terminator (1984)
arnie does what arnie does. superb film that launched a brilliant series of terminator films.
cult classic sci fi movie starring a young matthew broderick. about computers and global thermonuclear war. you will want to play this movie. obviously the computer stuff looks a bit dated now!
blade runner (1982)
amazing film, set the mood and look for a dark grimy future. the directors cut totally changes the film (if you have seen the original that is!). looked incredible back then and still does the business.
escape from new york
kurt russell as the legendary snake plissken, directed by john carpenter, the USA president is trapped in the prison that is now manhatten and there is only one man who could rescue him. action packed and another cult following film.
1970s sci fi movies
invasion of the body snatchers (1978)
creepy, suspenseful, a classic. sort of sci fi as its sort of about alien invasion sort of. a must watch so you know what others are talking about.
superman (1978), superman 2 and superman 3
obvious sci fi classics but superman 3 is perhaps the best of them as it goes all outs for humour and you get to see a bad superman.
capricorn one (1978)
dont read any review of it or what its about. its about a space mission, thats all you need to know. its a good film and especially for the topic that it covers at that time. a whole generation of conspiracy children grew up having watched this without realising why they were into conspiracies.
close encounters of the third kind (1977)
awesome visually and for what it was saying at its time and still great today. for those who watched it as a child it will never be forgotten. prog rock aliens come to earth.
dont expect another rerun of westworld. if you do you will be desperately dissapointed. this is as different from westworld as you could get. it is a thriller although most will think it not that trilling. first use of 3d computer graphics though! the use of yul brynners gunslinger sums it up. but futureworlds idea is interesting in itself, even if this sci fi movie is not.
the rocky horror picture show (1975)
it involves aliens and sci fi. honest. if you have not seen it and you need cheering up then this is the movie for you. a film that everyone must see.
logans run (1973)
way out man and another classic sci fi movie. although it is old and is from its time it is worth watching man. the earths post apocalyptic population is controlled by a limit on your age, if you dont want to die when you get to that age you have no choice but to run and be hunted.
yul brynner as a robot gone bad in the wild west, for a movie from 1973 its great fun and still looks good as its not really based on special effects. there was also a follow up film called futureworld.
soylent green (1973)
another classic sci fi film based in the then future. famous opening and especially its ending. dark for its time.
1960s sci fi films
planet Of the apes (1968)
dated by its ape costumes but still a good story and with that classic ending. 100 times better than tim burtons surpising abortion remake. there ware a load more planet of the apes films in the 70s, now only watched by true fans.
fantastic voyage 
for its time a great idea and another of the few sci fi films of that era that can be watched. as long as you dont expect the effects to stand up to much but just enjoy the premise of the film and how old it is.
the day of the triffids (1963)
the effects, acting and film have dated badly but if you want to complete your science fiction classic film education then this has to be watched. alien triffid plants attack the people of earth who have mostly been blinded.
the day the earth caught fire (1961)
the earths orbit is changed by man, will the earth be destroyed or saved?