Are we talking alternative rock, old school classic rock, screamo/heavy metal or any and all kinds? I have favorites and likes in all categories really.
If I'm working out to hard rock though I prefer Drowning Pool's first CD before David William's died. That dude could flat sing on top of the traditional heavy metal voices that people do. When I hear Sermon or Tear Away there are parts I still get chills sometimes.
I would complain a little that it's not shaved...jmo.
Metallica, old Megadeth, Slayer, Tool, Disturbed, Godsmack, Avenged 7X, Chevelle, Pantera, FFDP, AIC, Judas Priest, Iron Madden, Motorhead, Black Sabbath.
I'm sure there's a lot I'm missing. Maybe I should list the ones I hate:
Nickelback, Shinedown, Creed, Alter Bridge