Stone is still the Def/Res toughness gold standard.
With a good end-game build, IMNSHO, Invuln is second place.
With a good end-game build, bio comes in a VERY close third.
With incarnates AFTER the Alpha, it really becomes a toss-up.
Of all the Resist-based sets, Radiation Armor, with it's medium regen and +Absorb, when combined with an attack set that synergizes well (Rad, Dark, etc), it's the absolute toughest of the Resist-based sets.
If you want AoE, look at your attacks and decide which has the right combination of AoE for you. Just remember, while you can cook SOME enemies to death, higher-echelon enemies require you to do more than just stand there and "aura" them to death.
Energy Melee looks to be a great deal better as an ST set now. Though, I'm trying it out now, and I COULD be wrong.