i see both with a "buy 10 get 2/4 free" deal from time to time.. a few dozen is the way to go... they will for the most part stick together till they relax/discover that no one is going to eat them... then they will spread out a bit and do their own thing.. the best thing is that both are good looking fish and they are cheap...
a handful of cories (take yer pick i like all of them) will keep the bottom of the tank active.. otos are also a nice addition for planted tanks... IMO they look like tiny lil sharks with sucker mouths.. such a rad lil fish
if you ever want something a bit bigger that wont eat everyone or overload your filtration check out congo tetras.. ive got a small army in my planted 55... very active and extreamly colorful..