What other fish can i add in my tank?

I have a 40 g breeder! 2 angels(1 small,1 med), 3 glofish, 5 neon tetras, 1 small rainbow shark! i have 1 big driftwood cave i made( with real store purchased soaked wood) and 2 slate caves i made, and LOTS of plants. What is a good fish to add bc i want 1 more fish(or 2-3) more small ones? Also can i add a blue ram or 2?