redtail is ur best bet. they can be aggressive to other fish in some cases. most of the time they get along ok. make sure when u go to buy one u know the diff between redtail and scomb. ur LFS might not know the diff.
go with redtails.
get familiar with their looks.
they will take non live foods after a while depending on the fish itself.
some can be very skittish and some a bit aggro.
they get around 18 inches which is the largest recorded so far.