I'm leveling DRG now myself, and so far it seems relatively straightforward, especially compared to SMN which I've mained for a while now. It is a bit different getting used to a melee perspective as opposed to the ranged caster's, but overall DRG seems to have a nice flow to it. I haven't played enough of SAM to know much, but based on what others have said it seems to be even easier to pick up the basics. DRG has a bit more raid utility, but if you're looking to do raw damage and little else then SAM is probably for you.