Wizards are the easiest I think.
Monks are only difficult until you get ~10 PV.
After that, with an eternium-two hander, monk is totally easy mode and you can write all the extra scrolls at the mere cost of a few points of power, not mana.
Assassins, archers, elementalists, healers, scum-rolled bards are all pretty decent ultra material.
Getting aols is not such a big deal with the extra random caves and FGJC/IQD
They will either produce one directly or provide indirect means of obtaining one - RoDS, potions of exchange, plenty of stackable rings, or even a wand of wishing which I've found three times in FGJC in 10 games.
"Hell is empty and all the devils are here."