Actually you can mix them although some species tend to crossbreed but none in your list should. I'd get mystery snails. Make sure these are Pomacea bridgesii. Most of other species are voracious plant eaters such as the famous P. canaliculata.jackdaniel;2438585; said:I see your point, and thanks for the link.
I think I may get a few ramshorns, mysetery snails, or trumpet snails in addition to the shrimp to make the tank more interesting. Is there a reason I would want one type over another?