Yes HE-400 it could be bothering your brother and you since it's an open back
K550 will fit your genres except R&B, hip hop, rock and metal
Maybe take a look at Beyer DT770s variant? You will need a decent amp though
M50 is good but it doesn't have the speed and energy for your fast paced music like metal or hardrock. Superlux HD660 is a better choice for your genres but the comfort are terrible for me and need an amp.
AKG K181 / Shure...
I compared it briefly except the K701, from what i remebered the K550 is cleaner sounding, K550 has a blacker background, K550 has a bigger headstage than 940. The 940 is smoother and more enjoyable for music listening to my ears