All good suggestions, it gets down to "whatever works" or even "whatever you have". Fortunately, an oil drain plug is the easiest to access of all stuck bolts. (Usually, anyway.)
I'll add in two more:
Hammer on a cheap spline-type socket and then have at it with a big 1/2 ratchet or breaker bar.
File the flats, and then put a normal wrench on it.