I've done a lot of research on this subject, and most people say the #1 schooler is rummynose tetras and #2 is harlequin rasboras. Rummynose tetras are just super hard to acclimate to a new tank so they will have same survival problems as neon tetras.
Harlequin rasboras are suppose to be hardier. Also, I just went to a local fish store this weekend and saw with my own eyes that the two best schooling fishes were the rummynose and harlequin rasboras. I just ran my finger back and forth in front of the tank and they follow my finger very persistently in a group formation.