If you can run 5 dungeonbuddy, if you can't questing, less than 5 in dungeon have a great risk of getting player reported. Never did pure grind and I found that would be damn weird at blizzards eye a person that never does a single quest 1 to 85/90.
I start at 1 and stop at max level (unless it's a DK) Well, on a serious note, I've allways quested my chars.
I have always quested until i decided to buy 5 accounts and I must say 5man dungeonbuddy is amazing 3days 4hrs played time for 5 toons to 90 cant beat that in my books
This, and I usually toss in some ArchaeologyBuddy for the solo levelers when things get wonky in questing profiles (which hasn't happened much in recent months, yay!)
Did Monk in under 3 days with Kick's questing profiles, but most classes are in about 3 and a half days /played so the difference in levelling speed is not that different. One more option for tank classes is to solo farm dungeons, at least until Cataclysm ones. It needs a bit of tuning and choosing the right dungs, but it is doable with a full heirloom set and is probably safer than questing.
Some people hate questing, I used to level with dungeons and then they added xp in bgs and started doing a lot of that too. That was before honorbuddy, all I do now is mostly afk questing with logmeout plugin
Questing mixing with dungeons. When I hit 60 I start doing Hellfire Ramparts, crazy xp, it beats questing by far from 60 to 70