This is a post I have written for the wow-europe forums, so I would possibly like some feedback on it from here aswell, thanks for reading it.
Before I make this post I want to introduce myself abit.
I consider myself a pretty hardcore alter and I have levelled all classes accept for warrior-rogue to 70 and have done the 70-80 run 5 times on normal and twice on the WOTLK Beta.
I know nearly every quest by hearth and am usually a very fast leveler, getting upto ~6.5 days /played when I hit 80.
I personally donot use any sort of leveling guide, but I do use questhelper which is a really invaluable tool for leveling.
I am currently working on a spriest (77 with 5 days /played atm, expecting to be 80 near the end of the week) so all the statistics I note are from him, taken from my TitanPanel addon, which I believe to be 100% acurate.
I believe my knowledge of the priest class to be quite decent, averaging at about ~1200 dps on a bossfight in any normal instance.
Now if you managed to read my introduction, here is on to the real content of the post.
As you all know, leveling has been made more easy many times, by reducing XP needed to ding, increasing XP gained from quests and by releasing the BoA Items.
Because of this, leveling 1-70 is really a pisstake.
The problem with this is that, even though Questing has been buffed bigtime, instance XP never received the same threathment, maybe out of fear of people using high level friends to boost their low-level characters.
Before all these leveling changes, the best way to get XP was Instance with Quest>Instance>Quests, assuming that you had a good group, you could really make alot of easy XP in an instance with good players, compared with questing.
Currently with all the buffs to Questing its more like Questing>Instance with Quests>Instance.
I personally like doing instances, but here are the numbers of XP I get while doing the instances together with a good (!!!) group of friends who really know how to clear and are all very expd players.
BRD with quests: 2 hour run 98000 XP/Hour
At the same time however, you can do Hellfire Peninsula for 115000 XP/Hour
Ramparts and Bloodfurnace with quests: 90000 XP/Hour
UB and SP with quests: 110000 XP/Hour
Questing in Zang nets you 125000 XP/Hour
Personally I skip the terrokar instances so the next samples come from the WOTLK Instances
Nexus with quests: 185000 XP/Hour
UK with quests: 190000 XP/Hour
While however with questing in Borean Tundra you can easily get 250000 XP/Hour
AN/OK with quests: 140000 XP/Hour
Dragonblight: 300000 XP/Hour
DTK with quests:250000 XP/Hour
VH with quest:190000 XP/Hour
Grizzly Hills: 500000 XP/Hour
This is as far as my tests have taken me, as you can see it starts off with a little imbalance in HFP vs BRD of about 10000 XP/Hour, which makes about up for the better gear you will get.
But when you hit 75, the difference becomes completely skewed, with Grizzly Hills giving about double as much XP/Hour as DTK and even more then double as much as VH (which is understandable, VH is a crappy instance XP-wise)
I would personally advise blizzard to buff the amount of XP you get from instances and instance quests, so that Instance with quest is 110% of Quest XP and instance without quests is 90% of Quest XP.
This thread will probably be kept updated with more results as I hit Uldu instances/Gun'drak