Few things you have to decide first to narrow it down:
1. Do you want a single cichlid, a couple, or multiples
2. Do you want breeding pairs
Those are probably the first two questions to answer. It changes what you can put in the tank radically. If you just want a single fish, there are tons of options. If you want more of a community set up, it narrows it down a bit.
And deciding whether you want to breed or not changes everything as well.
OR
the other options is to find a cichlid you love that will fit in the tank (so max size in the 18inch range IMO for a 2 foot wide tank) and go from that.