The Spurs are gonna be a tough out IMHO. There is no guarantee the Lakers will win the series.
Still too much depends on the health of their Big 3. It's doubtful Duncan will be 100% by the WCF, he's playing through pain right now and he needs months of rest to really start healing. The Spurs will need him to dominate the paint on both ends. And then Ginobili is trying to come back from another ankle injury. It's a tall order to ask both of those guys to play at the top of their game with the injuries they have.
The Lakers have their own injuries, but they have shown that they don't NEED Bynum the way the Spurs need Ginobili in order to play at a high level. They can afford to integrate Bynum back in slowly and let him find his way again. If I were a betting man I'd put my money on the Lakers.