Helltides until 70 and then NMDs until 100.
Play WT2 and go to the boss summoning until 45. Run around and open all the chests until 50. Do the capstone. Go to WT3. Go to boss summoning and hit 58 then do the capstone. Go to WT4 and hang at the boss summoning until 70 then do NMDs until 100.
I have made nine level 100s this season. (4 Barbs, 2 Sorcs, 1 Necro, 1 Druid and 1 Rogue) This is generally one of the quickest ways to level. You also get a lot of rep towards getting a spark.