Well. Rain has cyclone armor, which gives about 200 elemental damage absorb, and 7 mdr. This may outweigh the 45% all res from gloom, if you don't play aggressively and attack yourself. The 5% ctc twister may stun some enemies if you are attacking.
Rain has +2 skills, which none of the others have, which would be a big bonus to the summoning tree. Big mana boost, making that a non issue. 30% lightning resist, slightly helping offsetting the lost 45% all res from gloom. Lightning is probably the most important resist.
Aldur's with the synergy would give a decent dexterity, strength and some viality boost, but i don't think that outweighs the bonuses that rain gives.
I'm voting for rain.
However, should you choose to go for the entire aldur's set, then the armor would be better.
This post was edited by Taurean on May 5 2022 04:02pm
D2:R