if you wear training gear and rock xp pots you will probably get to 50 doing only dolmens and getting the skyshards for your alliance. and I would recommend that because you need those skill points.

The fastest way to get to level 50 would be grinding. I wrote a guide on how to do it here which goes into detail on the areas for each faction and the buffs that make it faster. The short version is get training gear (Seducer for Magika, and anything that gives Stamina regen for stam builds so you don't run out of resources), Regen food, ESO Plus, Crown Scrolls or Ambrosia's and Ring of Mara if you have a friend . Then go to places like the Orsinium public dugeons (they can be packed with people sometimes) or your factions zones with are usually empty and kill everything. When I did this I got my Templar to level 50 in 15 hours of playtime which took two and a half days.