One of my favorites are rams. There are many varieties, including gold, german blue, electric blue, and black rams; all have longfin varieties, too. And all are fine in ~10 gallons. There are very easy to breed and the fry are fairly easy to raise as well. They only take about 3 to 4 months until they're ready to be taken to new homes. Keep them warm. Feed them live baby brine. Master breeder Dean has good video on them. these are my dark knight rams. 3 have the pitch black, the one up front isnt as hood quality.
Another easy fish would be the white cloud minnow. You can keep them in room temperature and they look amazing. The males will spar and show off to each other. I give them fruit flies to encourage breeding. They scatter their eggs and I see new little fry all the time. They're easy to raise too. I feed infusoria, live baby brine, and crushed Sera staple pellets. Here are some of mine. Sorry for pic they're fast.