I leveled a rogue, druid, priest, and warrior to 60 in vanilla
I cant comment on rogue because it was my first toon, druid was a leveling beast(pun intended), I leveled my warrior mostly tanking dungeons(needed to learn to tank like a boss) which was a blast... the priest however...
I mean, she could kill stuff just fine eventually.. tbh I dont remember specifically why I hated it- except one instance in stv where killing trolls was taking forever... but I remember it as being excrutiatingly slow, and drinking alot. Also my character had to drink alot for mana..
I think I ended up healing dungeons for alot of it
That said, I am debating leveling a priest as well, but I may be just a masochist xD