The Gasol trade, but only because he fits the Lakers much better than Shaq will fit the Suns.
Both trades were steals though because Marion's production can easily be replaced by the combination of Diaw and Amare (when Shaq is on the floor), plus Marion was probably going to walk in the offseason anyway. Banks was a throw in and they didn't want him anymore. So they got Shaq for free as far as talent goes, but the cash is going to hurt them.
Hard to say. Pau could well elevate the Lakers into legit contenders if they aren't already, and Shaq, well it remains to be seen if D'Antoni will scrap the run and gun style while Shaq plays and revert to more half-court sets.
I'd say Pau's move to the Lakers. LA seem to have spooked their fellow contenders into desperation trades, or at least talks.