id say you could cut down on the neons if you feel the need, but you don't necessarily have to. DEFINITELY get more Cories because they love being in schools... and they are more fun the more you have :P Also i wouldn't cut down on the oto's because not only are they great tank cleaners, but they like to be in schools as well.
I definitely think you could go for a pair of angels in there for "centerpiece" fish. Or if you don't like angels, maybe some sort of gourami... but i love my angels
If you just buy 2 they won't necessarily pair up, but they will probably be happy together. Ive even seen people who just keep one angel as a centerpiece... I always buy them small and watch them grow out, mainly because I am trying to get a "breeding pair" but also because its cheaper.. LOL
Oh,and i also had a male betta succesfully with angels on two different occasions, but now he has his own 1 gallon home and i keep a female betta in my community tank.