I don't live in Champaign anymore, but I did spend a few years there, and those years may have colored my feelings about Mas Amigos in comparison to its competition.
On its own merit, Mas Amigos is a no nonsense kind of place which provides very fresh chips and salsa and the food is decent.
However, given the choice to go to any Mexican restaurant in the Champaign-Urbana area, and having tried Mas Amigos out, I think that I would still head over to El Toro or Dos Reales. Old habits die hard.