These are essentially the easiest dungeons (some mechanics aside). You have your poetic gear at the best possible level to hit these up.

Of all the options, that's the first thing I run if I ever find myself looking for those tomes. There's little to no stress. I'm always rolling the wheel for whatever comes up in Wondrous Tails.

If you want xp, go for the leveling dungeons. If you want the top tomes, do raids or the 90 dungeons. There are plenty of other options. It's so easy to cap them. We don't need another source.