Master, because I like the slightly added challenge in builds that allow it, and kinda frustrating feeling in the beginning when I'm not doomed to win everything and actually have to flee quite a bit, depending on my eagerness to explore dangerous places of course. I tend to use only one crafting skill, but I do the other two mostly for the money in order to buy the skills I don't feel level up naturally (based on the cowardly way I play I guess

).
Also, since I pretty much have to save spam (due crashes) with very limited logging in the game, I think master is about perfect for most builds. I wouldn't say this if the game had more hard core death penalties, which I'm kinda against due the crashing problem. It is outright tough in the beginning, where you have to flee a lot and load spam in trapped areas against hard enemies, and plan better what approaches the game allows you and utilize these more deliberately.
But now that I'm quite familiar with the Skyrim beastiary (if I see a certain enemy and I'm low level, I'm now smart enough to choose another route or wait it out), even master isn't that much of a challenge anymore without nerfing the game, which shouldn't be required.