[Jei]

i quoting my own reply from other thread.

blm and whm both are good. some situation you'll want /blm, some situation you'll want /whm. some good thing about each sub

WHM has a lot of low level spells that rdm doesn't. at level all the way from 1rdm till 40rdm/20whm you get tons of additional spells to play with. Status correctioning, curaga and goddess sign. goddess sign works perfectly with convert while spells like poizona, prana, silena etc can safe your party more than you can imagine. Enemies that can hurt your status such as crawlers, mushrooms or skelletons using /whm is very helpful.

BLM in the other hand, their useful spells start to kick in at around 20+ (and warp at 17) from 1rdm till 30rdm you don't really get much additional useful spells to play with except drain and warp. Not until you reach 50rdm/25blm where you get frost and tracktor that are useful to the group. Frost lowers enemy's AGI so it helps your group to hit easier, everyone loves it.
BLM's best use is at 58rdm/29blm when you can get escape. that spell is a life saviour most of the time.

Personally, as a good rdm you should be ready to sub both WHM and BLM depending on the party combination. If there's no WHM, /WHM will help a lot. (BLM won't care to cure youso much when you convert. goddess sign is your best friend) while in the other hand if the group is lacking BLM, using /blm will help tons as well.