Can’t say what’s ‘best’ but I can say I’ve generally had a much easier time as Holy, and have cleared I think two layer 8s and one layer 7 (got stuffed by Patrician Cromwell on that one) as Holy, in the 180s ilvl wise. One of the 8s was pre-nerf, and I came out of level 4 with maybe one life to spare. The biggest advantage I think Ret has is more interrupts, but if you get the combo of anima powers that give you three extra charges of Hammer of Wrath, a chance to stun with HoW, and a chance to proc HoW with Judgement, you’re in really good shape against most bosses as Holy.
I’ve had fun with Ret and cleared up to layer 6 as Ret. Word of Glory is more like Word of Godly in there.
No idea how Prot is.