I received some interesting questions via my Twitter feed lately about what is the best way to level a druid. Honestly, it is an interesting decision, even more so with Cataclysm coming out and getting class defining abilities at level 10. Let me go through each of the specs and give the pros and cons of leveling that way.
Restoration – The advantages of leveling restoration is that you get pretty quick queue times in LFD. The disadvantage is that you really can’t do much else. You may be able to kill some mobs for quest with some balance spells, but they will be nowhere near as effective. Unless you really want to level as a healer as a challange, I would probably avoid this one.
Balance – I love raiding as a balance druid. Leveling is a bit more difficult, at least until Cataclysm. You don’t get Moonkin Form until you are deep in the Balance tree. You don’t get Eclipse until you are deep in the Balance tree. You don’t get Starfall until the very end of the Balance tree. In Cataclysm, this will change. The advantage is once you get all of these things, you can start to kill stuff quickly. But that is not until level 60. Nothing better than Starfall, Barkskin, and Hurricane a pack of mobs. Of course, you also have downtime regaining mana, even with Innervate. Also, using LFD may mean some wait time, especially before you get duel spec at level 40.
Feral – My raiding love will always be Balance, but my leveling love is Feral. Why is that? First, there is very little downtime. If you are questing, you go cat form and like a rogue, you can kill stuff before it even turns around. If I am using LFD, it is instant tank queues. It is by far the fastest leveling spec definitely before level 60 and more than likely after level 60. And in Cataclysm, it will still be the fastest way to level since everybody will want to be in LFD to see the new content. Second, you have the forms from level 20 on. You can start tanking at level 10 as a bear and you can start DPSing as a cat at level 20. Third, you can change their color by going to the hair salon. I love my white polar bear. Finally, people love bear tanks. Swipe spam plus glyphed Maul means most DPS can burst out AoE immediately. The only tank I have seen it similar with is paladin.
So what does this all mean. Here are my recommendations. Pre-level 60, no question, it is Feral all the way. (At least until Cataclysm). After level 60 and you can pick up Starfall, you can Feral or Balance, but I still prefer Feral in my opinion for speed. Resto is for the people who want a challenge while leveling. Not necessarily the fastest, but still okay.