Best way to level your level 50 alts to 51

[UltimateAoe2]

Same way its best to level 51-60 currently... Northern Thanalan fates.

Efficient way is 50-55 in N Than.
Once you hit 55, spam the Aery.
57, the Vault
59, Library.

Then you're done. Make sure to do your daily hunt marks (level 1, 2, and 3)!