i tried a few places and this is the best I found
parthians in a big group, good respawn
i split them into 2-3 groups because they would spam knock me down but if you are a chad shield gamer you can probably just pull all of them
could shave off over 30 minutes by just knowing where to grind
still about 500 exp a mob (level 61) so I don't know about grinding much higher like this