Haha,I remember Bard kiting in the low 40s in Dreadlands,3 levels solo in under an hour and that was after a nerf even - nothing like that on SoD.
Have a 55/100 AAs bard pretty twinked out,partially raid gear(and i dont talk about adepts) - quite weak compared to other classes at that level
mostly because he needs a lot of attention.At high tiers I am always impressed what they can do.
Key to leveleling/xping fast on SoD are damageshields,playstyle is more Diablo like,instead of getting singles,slow them and tear them down somewhat slowly
as on live you get a bunch and let them kill themselves on damageshields.
So you want a class with good damageshields and as you *need* a porter too the choice is clear,welcome to SoDruids.

From the tanks Warriors are highest dps,probably best for leveling,though I'm not a big fan of them,same problem as Bards,requires a lot of attention and button
mashing.
End game - I tell you which classes are *not* needed that much:
Tanks - too much high tiered tanks around.
Shamans and Beasts - you want exactly 1 of each in a raid,both classes have specific problems I dont want to repeat for the 999th time.

Enchanters - you dont want more than 2 in a raid,though they are great to have in groups (unlike Shammies and Bsts).
As always,play what you (and your buddies) enjoy most.