Do you read comics based on existing properties? Not your comic orientated Batman, Superman, Spawn, Spiderman or whatever but comics based on things.
They can greatly expand the universe and become better than the original source (transformers, GI Joe, Star Wars) or they can be very stale and rarely digress from the source material.
I'm a big fan of certain licenses such as (yeah I know) Transformers. Where the current continuity with IDW started everything fresh, and it's like the most complete universe I've seen in comics because it was designed from the start to be this very specific story. But Star Wars Empire/Rebellion is an example of a liscenced comic which goes above and beyond everything the movies are, and I think it's perhaps the best example of a perfect comic. The stories are mainly standalone, with the occasional multi-issue arc, but they focus on the obscure individual characters. The stories aren't based on referencing some over-arching point or focused on epic battles but provide digestable content, more focused on those obscure characters.
The X-Files comic is a great example of one which stuck to it's source and followed it. It didn't get ambitious and try to reinvent the wheel, but followed the motw style of the parent series, alternate tales of Mulder and Skully and situations which the show's budget couldn't always accomidate. It's art mainly hard lines and high contrast, some issues had painted sections for example to show the mania of characters. Doctor Who comics likewise provide alternate adventures, which could not have been shown on TV (well with the show's current budget, they could now). Aliens. Those comics were generally based on the novels but often just provided us with more alien killing fun. But I think as I've grown up a bit, the overly blatant themes of the Aliens comics do more to grind my gears than anything else. They lack the writting of the first three movies.
But there are some comics which are basically shit. They provide nothing new and are much worse than the source material, such as for example Predator. The predator comics are all essentially a retelling of the first two films just like replacing drug gang with russian secret service. What information they provide about the Predator culture is essentially meaningless to the story. The only good Predator comics seem to be against Aliens or Batman.
Resident Evil is another example, the comics are essentially Claire in tighter clothes fighting zombies more violently, with no real plot.

I might read one if it's based on a property I really like, e.g. 'Firefly' or "Evil Dead'... But generally I avoid them...
I think the main problem with a lot of them is that they spend more time trying to copy the original franchise than actually trying to branch off from it and be good in their own right. The 'Alien' and 'Predator' comics you mentioned are a good example of this: Instead of trying to actually make the series more interesting and providing an interesting backround to the movies, they just honed in on the most popular element of the original (marines vs aliens, predators killing stuff) and repeated it over and over again.
I haven't read 'Transformers' or 'GI Joe' or whatever, so I'm willing to accept that there are good franchise-based comics out there... But I still prefer to stick with 'original' comics.
ROM Spaceknight rules, though.

The Disney Gargoyles comic is the only comic i still read, and is basically what the show would have been after the end of season 2, if Disney hadn't fucked things up.  Its really good, and does a few things they could never pull off in the show, like all of Issue #7 and the occasion extra violence and cursing(not too much though).

I also read some of the Futurama comics(probably all the issue that had been out at the time), but i didn't stick with it.

hmm the futurama comics are pretty good, and the simpsons comics are actually better than the tv series imo.
Some random liscencing news that no-one cares about but the G.I. Joe comic has been brought by IDW, and will be getting a reboot. This is kinda tragic as the G.I. Joe comic through Marvel and DDP has been one continuity (with the occasional "elseworlds"), and has gotten pretty solid. Unlike most long-lasting comic series' this did see a change as time went on and from it's humble beginings to it's epic war stories as a reader it was such a rewarding comic. I know IDW will do a fantastic job with the reboot (just look at what they've done with Transformers) but this is verymuch a shame, because they could carry on the same continuity but use some of the newer characters so the roster aren't all 70 year olds. Last time i was this annoyed with comics was when DC decided to kill Azrael.