I might even put the BST epic in the S or A ranks; it has a click pet buff that never gets replaced and seems to stack with everything else: http://everquest.allakhazam.com/db/spell.html?spell=6278 Not that I've ever bothered to go back and get it... just seems silly that when I returned in ~ 2015 I'd have to go back and do 11 year old content. (OOW being from 2004) but here we are... now 2018 and there are still several classes who's 1.5/2.0 has an effect thats still useful and only obtainable from that ancient content. (I know, some people enjoy going back and doing em... I'm just not one of em.)
I primarily play a paladin and my epics (1.0, 1.5, & 2.0) were quite useful when I got them as current content. But, as a paladin who does not raid, they are for me almost always relics of a bygone EQ age now. They were fun to get though and I am glad that I did get them.
Paladin 2.0 has a self healing mod which stacks with a bunch of stuff including cleric bps which also boost heals. 1.0 is useless but looks awesome when made into an ornament.
Paladin 2.0 click doesn't stack with the healing focus on Armor of the Inquisitor or group AotI. So only useful when those two are down which is only ~10% of the time. I guess since the proc has a stun(level limited), you can say that helps on aggro. It really needs to be a group click like SK so it boosts the Paladin's healing. Rogue 2.0 is one of the best as well. Increases triple backstab by 45%. It lasts for 2 minutes and refreshes in 3 minutes.
Enchanter 1.0 epic clicky haste will stick on characters from level 1 and up. That's more of a novelty but it's something
Matter of perspective i suppose, and mine is what do their epics do for me lol. I also was basing it in must have. If we are going in terms of its almost required to actually play the class, i would say that the Necro and probably SK, are the only ones that would be of the "S" rank. Though, i am more often wrong than I am correct. On a side note, what us the origin of putting "S" before/higher than "A" when organizing rankings? I have never quite understood that.
S rank is some japanese thing that has spread to a lot of gaming. Anything below C is a failure, and ABC is too coarse a comparison so we've got SSS,SS,S,A,B,C... I don't really care to argue the rankings much because I think that everyone including druids (and other C ranks) should do their epics so they're all "must haves" to me. I do it even on my alts because I just enjoy it (especially the 1.0s). I just finished my mage alt's epic this weekend #neveragain. But to further the argument I don't care about, it'd be illuminating to compare priority of epics for a class with other aspects. Obviously any shaman or cleric worth their salt has their epic, but if you had a buddy you were building up and he had a spare weekend to play before you guys could group up again and could either hit level 110, work on improving their gear/augs or finish their 2.0, what would you recommend? If I was just focused on improving their character's contribution, I might tell them to do their epic, but for a ber/cle/rng I'd tell them to focus on hitting 110.
Personally, I would tell any class to level up first before focusing on their epic. To me that just makes more sense.