Arms is still very viable and is probably the best single target damage in the bracket. It's shortcomings are in that it doesn't have the longevity to stay up without a healer, and is susceptible to being kited once charge/intercept have are on cooldown.
Prot/fury are definitely not as popular with prot being great for soaking damage and controlling melee, but being somewhat useless against casters, and fury needing a lot of RNG + skill to be played effectively as opposed to arms having on-demand burst.