There is no 'best' all around class
WoW is a nice example of Rock-Scissors-Paper as far as classes go ..
You'll win against one class more often, but lose more often against another, esp. in duels.
In Battlegrounds, it will feel like you are losing all the time because you die so much, that's all - of course it depends on the skill of the player - you may watch a couple of duelers and think 'rogues always win' or 'warriors seem to always win', but another day of watching duels, you'd think something different..
Play whatever is the most fun to you!
~E