Green spotted puffers are the best in my opinion had them for years one of my favorite fish. Brackish isn't to difficult you just have to get a hydrometer and salt. Get a bucket for water to mix the salt for water changes. (that is the part I got tired of)
That is kind of what I read everywhere from people. I am not really opposed to it I guess. What's up with the "Abei puffer"? Is that just another member of the "target" group? A smaller tank and a single 4-6" puffer would be okay as well.
I have a hairy puffer in a 40B and absolutely love him. I use a larger gravel so he does not bury himself and is always out in the open. But all he does is lay around until feeding time. Though he has started puffing up in the evenings for no reason.
Sounds like for the type of puffer activity you are looking for a Green Spotted is the way to go.