I also have a 120 gal. Long tank. I prefer the boxy shape of the 5 foot 120 over the rectangular, thin shape of the 6 foot 125 gallon
Might be a good idea to remove the JD asap. Sooner or later the JD's fins are going to be nipped, or a tankmate is going to suddenly be missing.
I keep a mixed, mostly male African Community. A couple of predator Haps, a few more docile Haps, two Blue Dragons & Ruby Red Peacocks, Red & Blue Zebras, Trewavasae, Zebra Chilumba, Afra, Chailosi & Kenyi. Probably 30 - 35 fish, counting the five Botia loaches.
You have a lot of options with the bigger tank. If you want to add Mbuna into the mix, maybe add a well constructed rock pile.
In the past, I also included a lot of driftwood into the hardscape of my African tanks. Although it looked nice, something about the tannins made the set up look awkward. Once I removed the DW the fish became more active & colorful. My guess is the DW caused a slight drop in PH.
Your new tank looks awsome.