In a larger collection I'd rather have Alien. It mixes things up quite nicely and when you need to tweak things (and you will I bet), you have other games to rely on.

In a smaller collection I'd rather have Godzilla simply because it's more reliable. I've played it tons and it's not my favorite Elwin game because the play is so linear for me: short plunge, ramp, ramp, scoop, mode, etc. I love Avengers for the fact that every game feels different, and I find it far more challenging than Godzilla. I still like Godzilla a lot though, I'm splitting hairs here.

If I knew I could get an Alien that was error-free, I'd be all over that bad boy in a heart beat. That game drew me in on ball one. I was in a dark room with my wife and we were having an absolute blast. There's not many games that I vividly remember my first game, but I do with this one. Holy crap don't play it in the dark haha!