First one was on two of my ten first ever disks of amiga games for my miggy 500! Along with Leisure Suit Larry 1. I loved that game to death, and played it with my brother. But I wasn't very good and never lasted very long in these games. Still it was fun.
So I have to go for the first one, even if I just recently tried Tower Assault and were thoroughly impressed. Of course, every Alien Breed game have stood extremely well the test of time. Except the AB3D games though, they feel way too old. Strange that, the most technological advanced Alien Breed games feel so much older than the least technological advanced ones. Guess it's because Team17 did 2D graphics extremely well, and 3D wasn't far enough to even remind us of the quality of the 2D graphics on amiga.
Actually, 3D graphics toady is finally starting to catch up on the extremely polished 2D amiga games. Far Cry and Doom 3 being an example. If every game felt as "clean" as they are, I wouldn't miss the amiga so much. Maybe not.