The Illustrious Four

There are Four Illustrious Institutes of Magic.

Stonerang Institute

Seated deep in the Iron Hills of what was once Southwestern Altan'ruhl, Stonerang was originally founded by Aelrick the Pure as a source of hope for the people struggling desperately to survive the Orcs that also made their homes in the Iron Hills.  Survival was tricky, and travel even more so.  King Aelrick wanted to create an open school to educate the people seeking to prepare themselves for the dangerous lives they would lead.
Ascended of Stonerang often speak fondly of the classes and the trials the students must face.  It is noteworthy that the classes tend to blend students of different backgrounds and skills.  Advisors build "parties" to tackle various obstacles, almost one of which is always a Magen.   Ethics and morality are stressed at Stonerang.
Stonerang is the only Institute among the Illustrious Four that places no requirements or obligations on those who Ascend from its halls, whether as Magen or other, nor do they charge for their training.  

The Dark at Dagmurk

If Stonerang is considered "the light" then Dagmurk is fitting known as the Dark.  Students do not get to choose enrollment... Rather they are kidnapped from their homes and institutionalized, the exact criteria not being explicitly spelled out.  Life at Dagmurk is both taxing and dangerous.  Since they don't receive a tuition for their students, and they likewise don't auction those students off at the end, Dagmurk (like Stonerang) exists purely on donations and auxiliary services.  Dagmurk is likely a front for a far more lucrative Assassin's guild, and its Magen are often pushed directly into that line of work (although not exclusively).
Little is discussed about life as a student in Dagmurk, but most surmise that there are daily tests that put the Magen in life-or-death scenarios, making the road to Ascension a hellish one.
At the same time, it is far more unlikely to find an Ascended of Dagmurk among The Coalition of Ascended than any other faction.  By the time a Magen survives to Ascension from Dagmurk, they are often fiercely loyal and are quick to push the ideals of the Institute.

Flamewrought Academy

Flamewrought is the most academic of the Illustrious Four.  More of the study at Flamewrought takes the form of books and research than either of its 3 competitors.  Teachers known as Magisters each have areas of specialization and lore that they boast none others in the world could recount.  In their eyes, the theory is often more important than the application.  One unique feature to Flamewrought is that its Magen are often trained heavily in Diplomacy and world politics, making them valuable advisors to kingdoms as well as formidable magic-users in court.
Some of the Magisters serve in a recruiting capacity, going forth and finding prospective Magen in other towns and locales, all over the world.  No tuition is required, and the Magen are put in a curriculum that could easily take from 7-10 years to complete.  Where they recoup this investment however comes from those that Ascend.  
The Ascended of each year are auctioned off to the highest bidder to serve other nations, powers, factions, and organizations.  Fortunately for Flamewrought, their curriculum helps reinforce this concept from an early year, and as such most of their Ascended are not only expecting the auction, they take pride in being sold for the largest sums of money.
It is believed that Flamewrought either has a very powerful and versatile Reach, or some other method of Reaching from Splinter to Splinter.

The Hallowed Halls of Oceangarde

The Hallowed Halls primarily serve as a training ground for Magen, but much like Stonerang, they might also provide training for other disciplines of skill as well.  Admission to the Hallowed Halls is steep and does not always take the form of currency, but it is almost always considered worth-while as the Ascended of the Hallowed Hall are generally considered the most powerful and dangerous Magen in the world.  
The workload is heavy and focuses on the practical aspects of magic as it relates to supporting the Kingdom of Oceangarde.  Some of the Magen leaving the Hallowed Halls move on to other kingdoms and roles within those kingdoms, but far more remain in Oceangarde, enjoying the relative peace, stability, and prosperity of the "world's oldest city."  A few Magen go on to become Paragons, part of the elite military of Oceangarde.