Dungeons are fine for leveling up. They're not necessarily the very quickest route (I think, especially with the Atma madness as it is now, that FATE grinding is still the most XP/hour, and when you get to it, farming the first room of AV over and over with a premade is apparently stupidly good, too), but they're pretty decent.

After the daily roulette, you're better off selecting the top one or two dungeons from those available. Assuming all other things are equal (queue time(s) and likelihood of successful completion), that is. You might find it better to leave certain instances off the list (Aurum Vale has historically been extremely hit or miss as far as parties actually succeeding, but I haven't done much with it since 2.2). Regardless, do other things while you wait on the queue (hunting/challenge log, battle leves, beastmen dailies, FATEs).