I really don't pay attention to SM like that to be honest with you...
TVXQ is the only one and they have 2 members lmao
Chenle & Haechan are both main vocals, it's just that Chenle doesn't tend to get the standout lines like highnotes etc.... bcs his main strength is precisely that he is STABLE AF. Like this performance of No.1 5DREAM did really shows the state of their vocals really well.
Renjun does amazing when standing more or less still (and thus SM has him stand more or less still during his parts)
Jisung is passable
Jeno & Jaemin aren't good enough to get singing lines in SM
and finally Chenle is dancing for basically all his parts and is the only one you can hear during the chorus that is TECHNICALLY in unison