I never built a wheel, but always thought and-built is better. But recently I listened to a podcast with a wheelbuilder and he stated that the new wheel building robots got so good in recent years that even he recommends machine-built wheels for most people unless you really want a hand-built one. unless you really have confidence in a good wheel builder (and no, you average bike mechanic probably is not a good one) machine-built form reputable manufacturer should be good. and thsi coming from a wheelbuilder who live by hand-building wheels.

IF you are heavy (not sure if this is why spokes break, I don't want to offend you with that assumption), brass-nipples and double-butted spokes are recommended along with 36 spokes (normal is 32).