Lara is in a different league. Chavez jr will lose his next fight - he has got himself to a position where he has to make a step up to world level. Unfortunately he's not at that level. Arum knows this and that is why he's feeding him to Pavlik or Cotto.
Chavez Jr is improving greatly, but Lara is just on another league. To me Lara has world class boxing skills to make him a threat to anyone. Jr not yet. Jr in Mexican fashion is making up for lack amateur experience he is learning in the pros, while Lara has an extensive amateur background. My pick is Lara easily.