Either one would be fine for that tank. I have never bred the dickfeldi but have the J. marleri. I think they are similar but the marleri are a bit more aggressive. Julis are rock dwellers and appreciate a rock pile. They are cave spawners and you may not know when they spawn until you see tiny fry on the rocks. I od not do anything special, I just leave them in the tank until they reach one inch, then put them in a growout tank. I feed them finely crushed flakes. I do have a fair algae growth on the rocks and the tiny fry will pick at that too. I also give them frozen daphnia every other day. With the marleri it seems like they lay a few eggs every couple of weeks for two to three months (about 12 or so) so that there are babies of different ages. I am not sure if this is the same as dickfeldi.
The brichardi are also similar in that they appreciate a rock pile in which to spawn. Mine laid eggs every two months or so. The older juveniles will help defend the younger ones so you can end up with a colony. I find that behavior to be interesting and you can have many hours of enjoyment just watching the social behavior of these cichlids.
I do add epsom salts and SeaChem Tanganyikan buffer to my Tang. tanks but for the most part they will adjust to regular tap water.
Hope this helps and good luck. Keep us posted.
I have never kept plants in a tank with brichardi but I have seen some peoples tanks that have. I think it is possible as long as the plants can handle the higher pH.