I'm not picky about extra terrestrials, as long as they're used well in a story. One thing I think I don't like though, is when some show or movie has some weird complex and wants to show "what aliens really would be like!" as I find that rather annoying. I feel since aliens are completely fantasy, any way that a storyteller needs them to be for her or his work is perfectly fine by me. I read somewhere that the creatures in Signs aren't aliens, but rather they're demons. I feel that makes a lot of sense to me, especially since that movie mainly focused around religious themes.