Thanks everyone for the replies so far. I'll respond properly to some of these later but feel free to keep them coming.
There are some interesting ones here so far - the Super Crate Box one in particular. I think the Amiga has a lot of Snake-style games so I will steer away from that. Bejeweled probably doesn't have a version that runs on a stock Amiga but I think that will be some way down my list to be honest.
Will do a bit more research on some of the others tonight - hopefully by then I'll have some more to look into and think about