All I got to say apart from what was posted is that as an Elvaan your INT will be really low. Since it's low, your black magic will suck... and it will continue to suck until you can afford lots of +INT equipment. WHM may be more beneficial because you have high MND and when you can afford +MP equipment you can be a better WHM.
I won't say not to be an Elvaan mage, but to help your decision, you have to look at the big picture.
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Also...
Summons do not suck, it's just that people expect them to be Godly attackers that can destroy anything. The few that do continue their lives as SMNs will eventually be able to use whatever new abilities that Square Enix puts into the game.
Remember RDMs used to suck and no one wanted them in their party? Well now with the update and new spells, RDMs are a very sought after job for their new spells... they may even get more invites than any other mage now, and they can replace BRDs in some tasks.
As a SMN you have to think that your summon's abilities are going to help the party a lot, not that you're going to do hellfire, heavenly strike, or mega flare and do 23,000HP damage. Later on as SMNs get higher levels, we may see new summon abilities that are actually of an attacking nature that are similar to the amazing attack power that summons usually have in the main series, but for now the real power is in supporting.
A summon that can cast blink on the entire part is great. Raising attack power is awsome. Enchating weapons is amazing. Raising defense of the entire part is even more breath taking. Things like that are what makes a SMN so great.
The game is not over, and nothing is set in stone. Nerfs will continue, other classes will grow stronger. So... be what you want.
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BLM/WHM: Do you want to be a nuker and a backup healer? You'll eventually learn ancient black magic which are the strongest attacks in the game so far. You'll be a nuking force, and great for all kinds of intense battles. That's all you should think of when deciding on being this.
WHM/BLM: Do you want to be a healer/buffer and a useful aid in general sense? You would eventually be able to teleport to many places, as well as use BLM's "Home Jumps" to continue to support your party/alliance. Other than being a cab service, you can raise people(like you mentioned), and also cause damage to undead monsters by curing or casting Holy-type magic.
