I like them both, I have them on display in my chug cases, with Terradive as a stand in for Hooligan, along with Skyjack(fall).
If you like clear plastic I'd go with Space Case, but it's a fantastic mold and you should try to get them both.
I started a thread with this same question a while back, don't think I made a poll of it though. Anyway, from the positive remarks in that thread I decided I was going to get both. Since both were hard to track down here in Hawaii, I ended up grabbing a Terradive off of ebay first. I was pretty stoked with him overall, and had no luck finding a Spacecase in stores, so I ended up being satisfied with just having one of them. So, obviously, my vote goes to Terradive.
Space Case definitely beats out Terradive for me. The colors and headsculpt are appealing to me. The translucent plastic is a winner as well.
Thanks. Everyone keeps saying that its a great mold. Am I the only one that's had problems with its legs?