I've seen this dichotomy a number of times on the ladder, and I've become curious why some players and sets are more willing to place their faith in hax than others. The higher up one goes, the rarer things like Ash-Greninja with Surf become but the more frequently I see Charizard-Y carrying Fire Blast over Flamethrower.
I don't really have numbers to back me up here (and I would appreciate if someone would point me to them), so I'm curious to hear about why accuracy is valued over power on certain offensive sets and vice versa. On what sets have you found Flamethrower more useful than Fire blast, Surf more useful than Hydro pump, HP Fighting more useful than Focus Blast, etc.?