I agree, DRK (and IMO WAR) are pretty boring and DRK is a mess design-wise. I frankly gave up levelling WAR after trying a few dungeons and realizing it's not going to change looking at the skill list.
PLD and GNB feel really good to play, but balance is definitely important. PLD was excluded from groups in 3.0 for having slightly lower DPS because the game design so heavily rewards DPS. A fun job isn't fun if nobody will let you play with them.