Maxing combats is always better, at least in the Hippy Camp in Hippy Gear. The Frat Camp in Frat Gear is bugged, but who cares?
A noncombat gives you a 16.7% chance of your first outfit piece, a 20% chance of your second and a 25% chance of your last. It also gives you the same number chance at +100 mainstat. These things cannot be increased.
A combat gives you a 30% chance of each outfit piece, and 20 mainstat. These can be increased drastically using pickpocket, +ML and +items. Since you'll be outmoxing them before the script sends you there anyway, it's obviously better to do +combat. It can also be noted that if you get a couple of drops from a combat, that'll increase your chances of getting the last from the NCs just like getting them from NCs would.
Note that the numbers for the noncoms are reliant on the NCs being equal likelihood - in my (exceptionally limited) experience they're less likely but that might just be observation bias. It also ignores queue effects, but given the prior pirce of information, I'm really comfortable with that.