1" H. maculata - I REALLY like these!!! But they have very bad attitudes, a bad bite and are super fast from what I have heard.
0.75" N. chromatus - Kind of like a smaller version of a A. geniculata. I would get a genic over a chromatus personally.
4" Female H. gigas - It's cool because it can swim but other then that it does not appeal to me personally.
1.5" T. Ockerti - I would get one of these as a first choice. H. mac would be my second choice. Then gigas, then chromatus out of the options given. That's just my personal choices though...