40: sins and rangers thats pretty much it. A sage can do well in this bracket, since there will be newer players who aren't geared that you can nom, and depending on your fort, and hammers you can take down zerks, some paladins, sages, some clerics, wizards, necros, sins if you can catch them out, and rangers if you can catch them out
50: Rangers. Sage is probably the most OP in this bracket because of 2x stun hammers -damage taken mastery, and relic for -20% crit rate recieved. You can easily kill just about anything in this bracket (except for pallys, clerics, and some zerks)
60: Sins and rangers once again. Sage's don't do too well in this bracket, since every class (except the healer branch) has access to triple hit weapons. If you continue to use the same gears at 50 it still works well. I would advise getting the 60 relic, and 2h 60 hammer for when you catch out and want to 1 combo them (burn is super op)
70: This bracket is super easy for a myst (if you have pvp set) as long as you have your talents you can kill pretty much anything except a few AM's and props
80: Myst is even more OP (1h yellow hammer with triple attack) or the 2 handed hammer which has a stun, crit, and attack speed. Using staff will let you be able to kill anything with the exception of a players
90: Shaman is (from what I read) 2nd most OP class in this bracket. No other information available.