In terms of performance/Watt, the Intel core 2 duo series trumps every other mobile processor. They peform well, keep cool, and don't consume too much power. The AMD series are worse in every regard, but are generally cheaper. If you don't need ht power, the AMD will do you fine.
The first and foremost factor is budget and then is the required performance. So sort these out and then start looking for the best laptop in that budget.