SCH or WHMFollow

With the subjob system there's nothing like a final job. Level them both to 49-50 as WHM/SCH and SCH/WHM are pretty common combinations. You'll want to do some RDM and BLM leveling too to have a larger variety in spells from subs and magic attack bonus. Once you're done with that you shouldn't have much problems figuring out which mage job you'd rather be playing at higher level.

While you have summarized both jobs pretty well, it's important to note that White Mage is far more of a pure support job, offensively you'll be doing very little as White Mage. Presently, the primary differences between the two, from a support aspect, are essentially Haste, Cure V, and Raise III. White Mage also carries with it the benefits of Esuna, Sacrifice, and more potent Curaga spells. It is the clear winner from the support perspective, regardless of Accession's immense versatility.

That being said, with the level cap increase, SCH/WHM will gain access to Haste almost immediately, SCH/RDM obtaining it at a later level, along with Refresh. At that point, the most significant differences will be status removal, Cure V, and Raise III.

Without taking into account any benevolent additions to either job, I would probably recommend Scholar to be your job of choice, unless you do certain events like Einherjar where Esuna and high tier Curagas can make the difference between success and defeat.

Now, the blunt truth is, there are likely to be some serious modifications made to both jobs with each subsequent level cap increase, so it's impossible to make a fully fleshed out suggestion either way. If I had to propose any single line of thought, it would be similar to what the previous posters have said, but for different reasons.

Level your subjobs, not just because you'll need them, and because it will give you an idea of what you want to do with your character, but also because it will kill a substantial amount of time, allowing you to see which job develops into more of what you desire. Depending on the status of your subjob's levels, it may take you as long as June to complete all four of them to 49/50, giving you the chance to see what S-E plans for both jobs.

There is one last thing to take into account, and that's inventory. Many people don't anticipate this issue, but for mage jobs, it's substantive. If your melee jobs don't share much gear and you're already stretched, White Mage is probably going to be your best bet. While I can't actually carry all of my White Mage's gear on me all the time, the overflow into my Mog Satchel is minor compared to the sheer volume of gear that my Scholar has and can use.

To give you an idea, for White Mage, you'll need Haste, Cure Potency, Fast Cast, hMP, MP, and I'd suggest HP (Galka or no, being able to get a larger Sublimation charge before an event is always good). Both jobs can also make great use of Enfeebling gear, and Enhancing gear has different benefits for each job. Scholar needs all of these things (though they're limited in their selection of Haste and Cure Potency gear, comparatively), in addition to at least two very different sets of nuking gear, and a more varied selection of JSE.

To further complicate matters, Scholar is far more dependent on merits, and being able to adequately play, and utilize all of the abilities of a Scholar requires a more intimate knowledge of the job, just as it does comparing Scholar to Black Mage. Macros tend to be far more complicated, and knowing how to utilize your gear to optimize your spells and abilities is just flat out more work. To abbreviate this: to play Scholar, you have to be scholarly.

This is not to imply that White Mage is easy, it's my main job, I play it 90% of the time, it is NOT easy. White Mage requires a great deal of knowledge of what a particular monster can do, how it affects your team-mates, what you can do to minimize and mitigate those effects, and most of all, White Mage requires superior reflexes. Where Scholar requires more planning and (appropriately enough) application of strategy, White Mage requires an intuition, an ability to anticipate what will be needed at a moment's notice and how you can best facilitate those needs.

Regardless of all of this, I wish you the best of luck in your endeavors, hopefully you can make a decision that suits your play style and makes you happy. I hope some of this information is helpful in both your choice and your efforts to play the job you choose at the peak of your skill level.

Well, it's not exactly a top priority, but a melee set for campaign helps a lot.

Also don't forget the Ah CRAP I'M NOW THE TANK set of equipment to get you to that safe place to die / Reraise! (earth staff, phlanx rings, evasion gear)

SCH is a bit of a godsend for a Galka tbh. You get the most benefit out of sublimation and the MP efficiency is second to none. I have both WHM and SCH levelled and I love both. WHM is the best healer in the game bar none, so if you like that then go for it.

The nice thing about SCH is that you have versatility. You can be a healer (and a very good one), you can be amazing in small group fights where diversity and defensive buffs are nice. For example I took SCH over WHM to Tier II VNM in North Gusta recently because being able to regularly aoe stoneskin/dispel etc was useful. And the DoTs are amazing.

SCH would allow you to do almost any fight BLMs and RDMs can low man. So if you wanted to join small group stuff, SCH is pretty phenomenal. I love it for Ugg pendants, Ix'Aerns and other things. In larger alliance fights, SCH in with the BLMs is a nice touch for weather etc.

WHM will always be my love but if I want flexibility and want to go play with the nukers, then I often use SCH over BLM. I use both, BLM is a lot of fun but I find SCH gives me some abilities with good gear that are really useful.

I carry a lot of gear sets but have to say SCH takes up a lot more room than WHM when done well. Yigit, goliard, relic, af(+1), some cobra, staves, emn/healing gear, nuking gear. Numerous torques and waist pieces etc. Still enormous fun and worth the flexibility.

So if you want a job where you can be of use in non melee situation, where BLMs etc are useful then I'd say SCH. If you want to be the best healer there is, WHM :)