I think you should just plant the 55 and do cichlids in the planted tank! ( assuming you are getting cichlids that are plant safe...) Im pretty sure that most African cichlids for example dont do well with plants. In either case I would put the cichlids in the bigger tank due to their territorial nature... whether it is planted or not. They are alot of fun to watch though! I have Bolivian rams and a golden ram in my planted 25 right now and it works out great! I also used to have a 55 gallon African tank a long time ago. The plants always got dug up so I gave up on that and just stuck to rock hardscape with crushed coral substrate and thats it.
- Matt M.