I would go with an mp10wes if it's in the budget you can find them used reasonable any side of your cube should be good or I have seen some people put them in the return section but be careful you don't wanna get the dry side wet
+3 on the tunze nano stream . As far as placement. I would it facing oposit from the in flow head on your cube any thing to make the water fully circulate without leaving to quickly a spherical shape circulation is best.