At level 19, not much can stand against a very twinked rogue.
At level 29, the same can be said for the very twinked hunter.

PvP is semi-balanced, more so for Arena 3's/5's then solo or large scale PvP, for PvP play at maximum level.
The game is also balanced for 10-man and 25-man raid content.
Because they're balancing two aspects, its never going to be perfectly balanced in either aspect.
And because they're balancing end-game, things can be severely broken at lower levels... and be working as intended.

I still give the same advice.
If you're looking to level, and win half or more of your PvP battles, then PvP is a leveling tool.
If you're not winning even 50% of your battles, then another approach will be better.

Once you reach the level you want to play at.
See how you're doing...

A lot of people like the 70-74 bracket.
As a 70, you can run Arena against other level 70 characters.
You have access to Sunwell (PvE) gear and the last level of LV 70 PvP gear, which will cost you a weekend of PvP to acquire.
As with any twink bracket, you can turn off the experience and once geared forever have the best gear... no matter how many seasons go by.
This is probably the most populated twink bracket.