There's a lot of good SF comics out there. Like all the previous lists, this one comes from my own reading, and doesn't even encompass all of that.
Orbiter- A Warren Ellis story about returning to space. With a shuttle that disappeared over a decade ago.
Invisible Republic- Hardman and Bechko tell a great story here. It's a story of revolution, and the aftermath of that government falling apart. Try to find the truth.
Trilium- An interesting Jeff Lemire work about love, time travel, and ultimately saving others. Format works better in issues than TPB though.
Strange Science Fantasy- This set of Scott Morse stories is as pulpy as it sounds. What an amazing bit of work. I think it's mostly kid safe, too.
Winterworld- Chuck Dixon won't work for Marvel or DC anymore, and I really want more of his Ice Age apocalyptic world. The novel, The Mechanic's Song is good, too.
Y: the Last Man- A plague wiped out all men. but this one. He spends a lot of time trying to find his ex. And running from women that want him, one way or another.
Rocketo- Another brilliant pulpy story. There's unfortunately only two volumes. Feels kind of like Flash Gordon.
Low- The artwork is, well, wow. The story takes place on an Earth where the surface has been abandoned by men, and now a probe may have come back. BTW, lots of mutations.
Captain Victory and the Galactic Rangers- Does this sound pulpy at all? NOOO. A bit trippy here and there, but definitely fun.
The Bunker- A time travel story, where the characters found letters to themselves. And one came back to make it happen the way they want.
Letter '44- There's a big alien ship with astronauts investigating. This is unknown to the public, as is the technology developed to fight potential hostile aliens. Begins with the passing of the project from one President to the next via a letter.
Trees- Um, I don't know how to describe most of this. They're not really trees, they're HUGE and dropped all over the world, and occasionally spew stuff that kills folks. Avoid the EM buildup.
Transmetropolitan- Yeah, I like Warren Ellis' work. This is a crazy world, and Spider is just the man to expose how deranged and debauched it is. While engaging in said debauchery himself, of course.
As usual, there's tons more that I'm not listing.
When you play Social Justice, the world loses.