I've had experiences with both the cans and personally, I think the Brainwavz give you a little more bang for the buck. Obviously the PL50 has unmatched comfort, one of the best I've seen, but its sound quality in underwhelming, especially the mids.
The M1 has a different sound signature. They have good deep bass and nice recessed but not rolling off highs. They do lack soundstage but the overall experience was better.
I'd go for the PL50 if comfort was my priority. Otherwise, personally, I'd choose the M1 blindly.