I agree with @TMRC Exotics, it's totally dependant on the temperament of the individual JD, and other cichlids.
I wouldn't go with anything larger than the 6" area or there will be a struggle for dominance. I would recommend the JD and 2 females of the other species, such as Convicts (I have found Convicts are probably the easiest combo with Jacks). The JD will more often than not take dominance in this situation. Having 2 'targets' I believe takes the heat of the subdominant cichlid and disperses aggression. This is just a recipe that I have found that has worked for me, others may have a different opinion.
If you get them while they are quite small and ad them to the aquarium at the same time they are more likely to be tolerant of each other when they are adults but thats not a given. The only issue is the smaller you go, the harder it is to tell gender in the case of JD's.
