I've too have found the 200mm F2.8 to be a great lens. I also own a 200mm F4 L IS, and can verify that the 200mm F2.8 is sharper, especially in the corners. I wouldn't hesitate to recommend it based on optical quality.
If you want the best possible image quality, a good prime lens cannot be beaten. On the other hand, the 70-200 zoom has IS and is a lot more versatile, so it may be the better buy if money is limited.