I recommend Badger Regdab lube over K33. I've tried Iwata Superlube, Badger Regdab, and K-33 Balm, and IMO the Badger stuff works the best. It's almost water-thin, so it's best applied with a needle applicator, but of the AB lubes I've tried it actually lubes (reduces friction so parts move more smoothly) the best by a very wide margin, and doesn't dry up.
K33 is very easy to apply in precise amounts and places since it has a grease consistency instead of a liquid, and it also doesn't dry up, but it doesn't lube nearly as well as the Badger lube. It has a rep for being high-end stuff, but having used it I honestly I think that's mostly based on who makes it rather than how it performs. It's good, but it's not the best.
Iwata Superlube doesn't really rate . Lubes about as well as K33 when freshly applied, but it dries out and starts causing sticking within a day or two. Does help with tip dry a little, but not enough to really bother with.
I wouldn't personally use anything petroleum based like 3-in-1. Probably works fine as a lube, but I'd want to stay away from anything that might contaminate the needle and cause problems with the paint.