I'm thinking #3 would look badass in a movie

I like the first one, and the last one. The first one because you're drawn in by the familiarity of the superficially raptor-like shape, but then as the alien features come, like the extra front leg and the jacked up jaw, out it strikes you hard that this isn't something of this world.

And I like the last one because it looks the most foreign, like an insect that's grown fungus out of its exoskeleton or something. Also given the position of its middle 'grabbing' arm I like that its eyes are more oriented towards the bottom of it's head so that it can easily look at the ground.

I like the tails of the first two, but the body of the 3rd the most

Number three reminds me of Zerg. I say yes. :D

Personally, I prefer the first one. The sleek design makes them seem fast and ferocious. Almost frightening. The use of the sickle claws makes people relate the alien to a velociraptor. Yet even with these similarities, The muscle design makes them still seem VERY alien. Don't even get me started on the head, it should be obvious how it compares to the rest.
The second design, I feel is more humanoid in stance and design, so I don't quite deem it as so much of a alien as the rest. The third and fourth design seem too bulky and muscular. They seem to have a bit too much mass on them for their frame.

3 and 4 are awesome looking.

Aliens crossed with Zurg I think you might have something here.

I like the second one the best. I like the combination of its lithe form but how it still looks strong and capable. Also love the regalness of the design. =P

I like number 3, personally. It's just kind of nice to see something other than a raptor. ^^'
Raptor designs may be cool, but I think the third design has a lot more originality going for it. It looks really front-heavy though. Could maybe use a larger/longer tail to balance it out.

I like #2 the best. It looks the most sleek, but I like the feather things goin' on in #1.

that's a tough one. they are all nice with interesting aspects. i might say 3, but it looks like it could have trouble walking/running well(?).

I like number 4's legs, as the look alien, but more functional than 3's. Also, depending on the type of creature you are going for, 1 has a nice predator looking head, while 4 looks calm/gentler. The first two seem a little too raptor-like; they look more like mutant things that aliens, especially 2.

i like the bottom one best, it's got a nice stocky head and the butt/upper tail looks awesome spooky