You'll find the best results in larger group play with a mix of both white mages and scholars, though two of one and none of the other will never make or break a group. Each has some areas in which it excels. When you have one of each those strong points are made stronger while those weak points are largely erased.

I bounce between the two depending on how motivated I feel on a given day. When I want to be really engaged and active I'll log onto a Scholar and micromanage my fairy while stance dancing to add supporting DPS. If it's been a long day and I don't want to have to "work" at it, then I'll flip to white mage & enjoy a more streamlined play style.

They both accomplish the same things -- they simply do it in very different ways.