Had to read up what 'SBMM' was after seeing it here - from what I could gather, it matches you with players of your skill level; surely that's a good thing though, as you don't just end up lording it up over lesser skilled players and always get a challenge?
That depends on if you want to play run and gun CoD or Rainbow 6 Seige. With SBMM, every match becomes a case of you have to play your best else you'll get stomped. So you have to play the game more tactically and slower whether you want to or not. Not to mention the fluctuating matches that if you have a few good games in a row, you know you'll end up in a higher skilled lobby for a few matches where you still get stomped. Until your hidden "skill" drops enough to be put back into a better lobby but win a few in a row again then rinse and repeat.
The biggest thing for me with SBMM though is games (including CoD) used to and many still do give you separate playlists for normal and competitive.