I don't have experience with OEM, but have used both Thule and Yakima on various cars. (I'm using Yakima feet bolted directly to the roof on my Subie.)
Depending on the weekend adventure, my '08 WRX hatch carries 1-3 bikes, a Yakima Rocket box, my wife's kayak, or any combo of the 3. It has super solid attachment points and I really load it up - I've never had any issues.
The rack can be removed in 30 seconds using the quick release between the tower and the the foot, but then you have 4 black pods sitting on your roof that may or may not detract from the aesthetics (you may or may not care).
Things to consider:
- DO NOT attach via Y-clips on the door jambs - they will eff up the rubber seals. Use the feet that bolt to the roof
- You will lose 2-4mpg running the the empty rack with no toys on top
- You will lose another 2 or so mpg with a full rack, bikes and boats seem to be the worst offenders
- The Yakima fairing helps with mpg, noise, and looks