Since he is not particular about any sound signature, better to get something cheaper and decent sounding for less than spend extra... IMO, at least!
PL50 and M1 are both balanced, but both will lack bass. M1 in addition will require a bit more volume (due to higher impedance). PL50 would have better sound stage, imaging and treble than M1. But, those are not signatures that may be instantly liked by everybody.
At that price (in the market section), I think NE7m is a very good choice, especially since your friend is using iPhone. Only if you are averse to buying used, you need to consider other choices.