1. EA
2. WR
3. EP
4. WF
5. WB
6. MG
7. PSY
8. MYSTIC
9. SIN
10. SEEKER
I say this because.. EA is all around the best 'AA' class in the game, able to purge and deal extreme amounts of damage in pairs.
WR is 100% the 2nd most useful class in all mass PK, because they are the ones who literally control the outcome of RG's, Pushes, Etc.
EP is no brainer, nobody is living with EP's.
WF? Nova's and AoE Purges.
WB.. Air-Knockdown & Buffs.. Yaaas.
MG? Ice Prisons and Nuking.
Rest are just nice to have, sometimes.