Once I bought a 5D3, I wanted something better and picked up a used f/1.4 to try (and sold the f/1.8 to a co-worker). The bokeh was better, and the AF performance was better, but still not as good as my ring-USM lenses. I planned on living with the AF performance for awhile, but found a good deal on a new 50L so pulled the trigger.
The 50L solved all my issues with the previous two primes. It's only downside for me was the size and weight, so I hung onto the f/1.4 for those instances when I was traveling and wanted to pack a small, light prime. However, I recently picked up a refurbished 40mm f/2.8 pancake that now meets that need, so I will eventually sell the f/1.4.
Just curious. Could you more completely identify the "50L" that solved all your issues? Lenses, I have noticed, have such similar names, it's easy to confuse.