"What’s your favorite movie?"

Ugh. It’s the dreaded question almost every movie critic or vocal cinephile is asked, much to their chagrin. It’s an impossible question to answer simply. Then there’s the inevitable, equally frustrating follow-up question, asking about my favorite film genre. If I’m in a mood, my response will be short and snarky: My favorite genre of movies is good ones.

If I’m feeling generous, though, I’ll probably say my favorite genre is science fiction. When done well, it not only entertains but immerses the viewer into an imaginative world of fascinating ideas, exciting action and memorable characters. Sci-fi gets the mind going just as much as the pulse … when it’s done right. And these five films (there are obviously many others that would be second-ballot members of my personal sci-fi hall of fame, but we’ll save those for perhaps another time) definitely do it right.

"Children of Men"

I realize that it’s pretty ironic to name my favorite movie after just railing on the question of my favorite movie of all time, but that’s where we are. 2006’s "Children of Men" is one of my favorite movies. It’s what I point to when I talk about movies I think are brilliant in almost every aspect of their production.

When I see a movie, I hope to be immersed into the movie and completely drawn into its world. No movie that I’ve seen does it as well as "Children of Men" and director Alfonso Cuarón. It already has an intriguing sci-fi scenario – in the near future, humanity can no longer produce children, meaning the end of the human race is near unless Clive Owen can protect the first pregnant woman in two decades – filled with fascinating and serious thoughts about our society and set in a universe that feels unnerving plausible.

There’s a lot to chew on – Cuarón fills the film with a thick immigration subtext and plenty of references to the political issues of our time – but his mesmerizing direction doesn’t let the audience’s mind wander too far. His camerawork, with the help of cinematographer/genius Emmanuel Lubezki, is brilliant, using a collection of long takes to absorb the audience into the film in a way I’ve never felt before. Two of the shots – a four minute uninterrupted attack on a car and another seven minute take of Owen running through an imploding urban battlefield – are some of the best sequences in film history, placing the audience into the action in breathless fashion.

Every time I watch "Children of Men," I feel like I’m in the shoes of a participant and witness inside the movie. It makes me forget that there is a screen between the audience and the action, and that’s some pretty incredible movie magic.

"2001: A Space Odyssey"

If "Children of Men" is the ultimate in immersive cinematic experiences, then "2001: A Space Odyssey" is the ultimate in cinematic experiences period. It is the definition of a trip, as Stanley Kubrick takes viewers on a hypnotic journey through the history of mankind. Between the apes of the first act and LSD lightshow/space baby of the last, it’s hard to make sense of it all, but that’s not really the point. It’s a cinematic Rorschach test, where Kubrick gives you the pieces, and you try to put them together and find your own meanings and theories. Even if you think you’ve put it together, there’s something new to find or look at.

Plus, wedged in between all of that artsy-fartsy raging monkey/space baby symphony pretention is a terrific sci-fi horror story about a killer computer in space. And if you don’t like that section of "2001" and think we can still be on speaking terms? Well, I’m sorry, Dave, but I’m afraid I can’t do that.

"Aliens"

The Alien series is one of the most peculiar franchises in Hollywood history. Each of its four films (we’re leaving out "Prometheus" for now) grabbed a different director and let him put his own stamp on the series, for better or for worse. After Ridley Scott’s craftily intense and often hauntingly beautiful first installment, James Cameron took the helm for "Aliens" and turned it into a massive, blockbuster horror action movie that somehow manages to not only equal but better its predecessor.

It’s a creepy thriller while also one of the best action movies to come out of Hollywood. While Cameron’s screenwriting is usually acceptable at best, his screenplay for "Aliens" is great. He manages to go bigger than the original film without losing what made it so great, and he helps evolve and develop a band of memorable characters that would be copied for decades by less creative writers. Plus, is there a better alien design than H.R. Giger’s aliens? No, there is not.

It should be noted that if you’re planning on rewatching "Aliens" anytime soon, pop in the original theatrical version, not the director’s cut. The director’s cut is about 17 minutes longer, but it feels like they added an extra hour. The extra footage weighs on the film and adds little at best. Plus, "Aliens" didn’t need any extra scenes. It’s pretty much perfect as is.

"Back to the Future"

"Back of the Future" is soft science fiction. Really soft, like a pillow filled with marshmallow fluff. Then again, no one is really going to "Back to the Future" for the science (though if someone ever manages to create a time machine with a DeLorean, they deserve every Nobel Prize). No, they are going for entertainment, and in that regard, it’s pretty much perfect.

Robert Zemeckis’s classic 1985 blockbuster is entertainingly inventive with its time travel shenanigans, but it keeps the mechanics pretty straight-forward, much to the film’s benefit (it’s no "Primer"). Instead, the focus is on building its band of characters. Most movies are lucky to have one or two memorable characters. "Back to the Future" has at least five, including Marty McFly and Doc Brown, one of the finest leading duos in a genre packed with iconic leading duos (Luke and Han, Kirk and Spock, Terl and Ker).

Thirty years later, fans still break down the hidden time travel enigmas and peculiar plot points. Why does nobody remember Marty/Calvin Klein after he goes back to modern times? Does it not unnerve George that his son looks an awful lot like his wife’s high school crush? Is Chuck Berry still technically the man behind "Johnny B. Goode"? We wouldn’t be debating these little plot holes if we didn’t love to revisit "Back to the Future" so much. No one analyzes the ramifications of time travel in "Timeline."

"District 9"

About seven years ago, Peter Jackson was attempting to get a movie based on the wildly popular "Halo" video game off the ground. He had his man for the job: South African first-time director Neill Blomkamp. Unfortunately, he didn’t have the funding, so "Halo" fell through and Jackson gave Blomkamp $30 million to make whatever movie he wanted. The result was "District 9," one of the smartest and most entertaining science fiction films to come out of the last decade. It even got a Best Picture nomination, and considering the Oscars’ hatred of, well, any genre other than drama, that’s quite the feat.

Blomkamp uses his South African childhood during apartheid to set up a fascinating sci-fi allegory, complete with a captivating (and mostly improvised) performance from then-newcomer Sharlto Copley. It’s a rare situation when you hope the action can keep the same energy and invention as the story (most big budget sci-fi movies have that reversed these days), but that’s exactly the case with "District 9." And in case you were concerned, the action easily matches the story in terms of originality and excitement.

If only all the other movies based on video games had gone through the same brilliant transformation.