A basic runndown of each class and what to expect. DK tons of tanking abilities, lots of CC, a lot of DoTs. Downside, lack of burst in PvP. NB, stealth, tons of burst and siphoning abilities nice teleport ability, a fear that goes through block, a lot of ultimate gen. Downside, very squishy with lack of tanking abilities, resort to stealth, shields and dodge. Templar, superb healing and group utility to improve group damage, useful tanking abilities. Downside, not so excellent dps solo compared to other classes. Warden, pve good healers, good tanks, not so great dps. Pvp superb dps with unblockable spammable and shalks while also being tanky.

Typical time to level any of these solo, 2 days, probably the better part of a day if you hunker down, have all the xp boosters.