If they havn't nerfed the Honor conversion too badly for Fragments farming (Used to be 3 Honor for 1 Fragment) it could be viable. Also when it next occurs, again assuming they havn't fixed it, winning the Events with the Battleground Bonus Honor buff could be viable but that really does rely on lucking out and getting into a team that wins events frequently.
Havn't personally tried Ashran since the expansion, I finished Warlord of Draenor leading upto legion so I've avoided it like the plague since.
I would do skirmishes for honor farming. According to my napkin math guesstimation they are by miles the most efficient to grind consistently for hours.