What would a Subaru be without a roof rack? Those cars were purpose built to carry skis, bikes, and maybe the occasional kayak.
I wouldn’t recommend buying a factory rack, though, at least not for the actual carrying pieces—they’re overpriced. Factory bars are fine, and you can easily attach aftermarket accessories to them. I mounted my Yakima Loadwarrior car-top basket ($269) to the factory bars on my 2005 WRX. I chose the Loadwarrior for its versatility: the basket can carry any type of cargo, and it fits both Yakima's Fatcat 4 ski attachment ($209) and the company's SprocketRocket bike holder ($189).
Although both Yakima and Thule would disagree, I don’t see many qualitative difference between the companies. Which you choose really comes down to aesthetics and whether there's a specific setup you want. Thule offers a similar arrangement to the one I have with their 690XT M.O.A.B. basket ($379), a Universal Flat Top ($170) for skis, and a 513 Domestique ($170) for bikes. And, of course, with either Yakima or Thule you can always do without the basket and attach the carriers directly to the factory cross pieces.