Cool ok so it would be great if you can confirm your hardness - maybe get a test kit but its looking like your water is generally soft and acidic which is great for a variety of species.
From your list if you want a planted tank you have a couple of fish on there known for eating aquarium plants like Severums and Silver Dollars as well as fish that dig like the Firemouth and Jack Dempsey. If you have the Zebra Parrots in your other tank do you really want them in both?
In a 125 are the dimensions 72' x 18' x 20' so you want to stick to fish that max out around 8-9 inches as adults, though a little under might be better.
I can tell you like cichlids, plecos and the community aspect so if it were me with your tank and your water I'd be looking at something like
4x Geophagus Winemilleri (or similar sized Geophagus - Red Head Tapajos, Svenii etc)
1x Threadfin Acara (I always think these look great with Geos - the Albino variant is particularly cool but you can't go too wrong)
8x Annostomus Ternetzi (or similar head stander - spotted, marbled, strawberry etc)
20x Lemon Tetras (or similar deep-bodied tetra - X-Ray, Flame, Phantom etc)
8x Flagtail Catfish (or similar chunky Callichthyidae like Brochis or one of the bigger Corydoras)
3x Whiptail Catfish (Sturisoma or Rineloricaria species - few other options too)
With this kind of stocking you have a gregarious group of Geophagus with a Threadfin Acara to keep them in check, a big school of deep-bodied tetras to act as dither fish, the headstands as a larger schooling fish for interesting behaviour and colour. Big school of bottom dwellers to zip along the sand substrate and get the muck into the water column and between the Whiptail Catfish and the Headstanders your tank will be picked clean of algae. The head standers can sometimes nibble plants but mine were pretty good in the past - you could replace these for something like a Hemiodus characin which is a more open-water swimmer or a bigger disk characin like a Colombian Tetra or Bleeding Heart Tetra. You could also swap the whiptails for some of the plecos you mentioned.
Just remember though this is just my personal preference, I've stuck to a South American biotope but you could mix in some of the barbs from Asia like Denison Barbs or Mascara Barbs instead of the Headstanders - Congo Tetras and the different types of African Tetra could also be a cool option.
Wills
