Instead of requesting what you should keep....... why not state what YOU would like to keep and then check here to see if its ok for that sized tank.
But if your just looking for ideas... then i would say some SA/CA cichlids like always, but keep ones that are not too aggressive as you dont have alot of tank space to work with.
Personally, I'd do 6 festivums and a school of charicins. either neons,cardinals or harliquin rasboras. in a semi-planted tank with a few nice pieces of wood on a black substrate/black background. (excuss the spelling)