SMN or BLM sub for whm?Follow

I currently been using blm sub for my 57whm but as of lately I have been slowly lvling my smn and as I can tell so far when I sub a 17smn sub instead of a 28blm sub I only lose 6mp So Should I just lvl my summoner to 25 for auto-refresh?

Bar-none, BLM is the best sub for WHM until lvl 50. The BLM sub is a bit more versatile for the different situations you may get into. You can use drain, blaze spikes, and the like for when you get hit, as well has have access to Elemental Seal for sleep, bio, ect. Granted with the SMN sub you have an extensive MP boost, however, there is not much else you can do with it.

Post lvl 50, it's really a matter of preference for which sub you use. BLM sub offers aspir, escape, conserve MP, and a few more dmg spells so you can do the occasional MB. However, with the SMN sub, you are more focused to buffing and healing the PT. You will have auto-refresh, blink, AOE Ice Spikes, as well as a considerable MP boost. Also, I've been asked to have Carby pull on occasion to avoid Links.

As a 51 WHM, I prefer to use the SMN sub for most pt's. However, I also have my BLM lvled in case I may need to sub it for some situations.