Actually...

Receivers do not have any regulations on providing accurate power ratings with all channels driven, while amps do.

Unless it was a bottom of the barrel amp, I'd get the one with more watts. If you're looking at good companies, the power ratings will almost always be accurate, unlike with receivers where the power ratings are often dishonest. I'd take a 380 watt Rotel over a 150 watt Bryston anyday - and I'd bet anyone that the Rotel would drive any speaker set better.