Rogue, Priest, or Shaman, which one is worth boosting? In WotLK Classic, Shaman is the easiest and most fun to level. So probably level that "for real".However, the other reason to boost either the rogue or priest is that the shaman will overlap with either one for heirlooms, so you can buy fewer heirlooms with the boosted one.Whichever class you choose to boost will get to 80 and will be in a position to buy heirlooms for the other two. But heirlooms can be expensive when you only have one max level toon so you want to be efficient if possible and buy the least number of heirlooms possible. You can do this by buying overlapping Wotlk Classic Gold that works for multiple classes. The shaman is a true hybrid class utilizing both agility and intellect gear and so you truly can use a wide variety of heirlooms for them.IF YOU BOOST THE ROGUE: You will focus on getting heirloom gear that works for both the shaman and the priest. So you will want the spell power mace, and cloth chest and shoulders (PvP or badge variety). These items will actually work on the shaman even if you want to level as an enhancement. (Remember that a slow SPELLPOWER one-hander, Wraith Strike, is best in the slot for enhancement in this tier. It's viable to level enhance with the spell power mace in your main hand. Second, spell power weapons have the same DPS as non-spell power weapons prior to Burning Crusade.) Alternatively, you can level the shaman as an Elemental caster if you desire or prefer ranged. And you will be able to heal as well no matter how you are spec'd with those three pieces up to Ramps with no issues. If you do level as enhance you can get an agility heirloom weapon for your offhand at some point as well. (NOTE: Lots of people say to get a 2-hand heirloom weapon for your enhance shaman prior to 40 when you don't have dual wield, but again that just ends up costing more badges/WG stuff. The one-hand mace will clobber things plenty fast 1-39.)IF YOU BOOST THE PRIEST: You will focus on getting heirloom gear that works for both the shaman and the rogue. So you will want agi sword or mace (or dagger if you want) and leather chest and shoulders (PvP or badge variety). With this mix you will sort of have to level your shaman as Enhancement, as Elemental will not be viable with an agility weapon. But that's probably for the best anyways. Bad Scenario to avoid: IF YOU BOOST THE SHAMAN: The rogue and priest do not overlap with heirlooms at all so if you want heirlooms for both you'd have to buy two full sets.HOWEVER, ignoring all of the above, the most important choice is what toon will keep you the most engaged having a high-level character NOW. Also, don't be obsessed with Discipline healing if it sounds boring... Holy is great fun.