eh, I could see playing both. Honestly, I would love to do wow classic for a while... but if they dont update some stuff, or role a different direction (wow alternate expansion, cap still @ 60?) I could see only subbing for 1 year or so.
Pantheon will be a while new world to explore... and I feel there are no other games that have really done PVE and developed it well, with cool lore and unique things. Pantheon is actually designing it that way. That is why if I HAD to choose one, it will be Pantheon.