Gaudion wrote:
Hybrid leveling is as follows.
Druids are slow until 10, agonizing from 10 to 20, and then one of the best leveling classes in the game from 20-70 if you level Feral. No downtime whatsoever, can tank instances until at least 60 without any gear checks. You can also throw on an off-set to heal from 1-60 or so.
Paladin leveling is agonizing until 20, mediocre-to-slow from 20-50, and good (though not great) from 50-70 if you level Ret. It's agonizing until 34 and decent from 34-70 if you level Prot. As Prot you will be able to tank any instance from your late teens to 70, gear allowing. Tanking is possible as Ret from 20-60 though highly discouraged. Either spec can throw on an off-set of gear and heal from 1-60 at least.
Shaman level decently from 1-10, retardedly slow from 10-30, slightly less agonizingly slow from 30-40, and extremely well from 40-70 if you level Enhancement. Elemental blows from 1-60, but once you get Outlands gear and Water Shield in your early 60's it levels very well. You can throw on an off-set to heal instances from 1-60, and tanking is somewhat possible around the late 30's range, but generally not recommended at any level as Shaman are not meant to be tanks in any capacity whatsoever.
I'm going to have to disagree somwhat as well. (Just a note, though, that I'm not 70 on anything, but I've got a 60 prot paladin, a 63 enhancement shammy, and 2 60 druids, balance and feral.)
Paladin is fine during the early level for the most part. It slows down post 20, but picks up as Prot once you get reckoning and holy shield. You have to be careful about picking where your leveling as Prot however, and you might be better off grinding as opposed to questing. Mobs that cast or do non-physical damage are a no-no. This gets worse as you get higher level, as mob spells are barely noticeable at low levels, but once you get into the upper 40s and 50s, mob's spells pick up their damage a lot. Gear is fairly important, which means if it's your first toon, I'd take 2 gathering professions.
Shaman, depending on faction, are very different in my limited experience (my only horde shaman only made it to 30). 10-low 20s is cake if you're a draenei. From there to 30 is...bad. As horde, I found 10-30 horrible, but I can't stand The Barrens (and this was pre-BC.) 30-40 is okay, though using a 2-hander with windfury, I felt awfully fragile and when windfury didn't proc the fights sucked. Once you pick up dual-wielding and stormstrike, it's a breeze. I found shaman to be one of the easiest to level post-40 (having a spell interrupt is soooooo nice.) Again, gear is fairly important.
Druids...what can I say. As stated earlier, 1-10 is horrible. When feral, 10-20 is pretty bad. 20 on is pretty easy, but once you get Pounce at 36, it pretty much becomes a cakewalk. Getting mangle at 50 makes it even easier. Gear isn't really that important (my feral made it to Outlands while still using a level 29 staff :) )
As for balance...don't level balance. It's kind of fun if you want to be a caster but don't want to be particularly squishy, but you will stop and drink constantly. I still have to stop and drink far too often on my 60 balance druid, as far as I'm concerned.
All in all, feral druid is probably the easiest, followed by enhancement shaman, then prot pally. You do have to be a bit more careful with a shaman, though, as shamans really lack an "Oh ****!" button, something pallies have in spades (and druids having to a certain extent too, particular after getting barkskin.)