Physical, 100%. Since I have a case that holds 24 games with the Vita, I'm not worried about carrying anything.
Plus, as others have mentioned... I, too, haven't paid retail for any of the 7 Vita games I own. I appreciate what Sony is doing by having the digital versions be cheaper, but it's still generally pretty easy to find even cheaper physical versions within a few weeks, if not less.
In addition to that, there's the memory card issue... I'd rather lug around multiple game cards that have to (eventually) deal with having to pick and choose what stays on the memory card. Even with a 32gb, the room will eventually run out, and I'd rather not have to deal with that problem by either being selective, or buying another overpriced memory card.
I understand the benefits of digital, but they still aren't enough to make me break from just sticking with physical versions of everything.