Here's my experience, and what I own:
15mm F2.8 fish, this is a great lens, and razor sharp too. Very good color and contrast.
14L Mark I, this is not a remarkable lens. Not bad, but not what one expects from an L prime.
24L, very good but a tad too soft wide open.
35L, most excellent...the best, perhaps the best 35mm of any brand. Razor sharp wide open.
50L, AF performance is sub par. When AF locks dead on and you know how to move your body to mitigate the focus shift, it is great, but when shooting close and fast the AF is dodgy...this is Canon's shame :-( And yes, it has been calibrated with little improvement. Why Canon chose to not use a floating rear element like the 35L and 85L is anyone's guess. Idiots!
85L, most excellent, and no other make has anything over this gem. Razor sharp wide open.
135L, fantastic, uber over the top amazing. The color rendition and contrast of this lens is magnificient.
200L, same as 135L
16-35L, very good lens, but not amazing.
24-70L, the best standard/normal zoom of any make, any brand. Razor sharp wide open, great color and contrast, and built for commercial-pro grade abuse.
70-200L F2.8 IS, a great tele-zoom. Very sharp wide open across entire focal range.
100-400 IS, nearly as good as the 70-200L F2.8 IS. This lens is very, very good for a tele-zoom.