I have used the 35 24 and 50 extensively on an aps-h sensor.
For IQ you much better off with the 35, IF the focal is what you need, they're very different. Second when it comes to sharpness you want the 35. However, if you need weatherseal, MUCH nicer bokeh, color and resistance to flare, you want the 50.
I use 24 and 50 on a mk4, and I love them both. But IQ of 50mm lenses will never match the equiv in 35 and 85mm. I hope they will, but it just seems like they haven't yet, so my money is on never.
If you want the best possible 50, and my god how wonderful the 50 is on both aps-h and FF, color, contrast sharpness from wide open (1,2) through 2,8, you absolutely want the 50L. It will never break and is in my eyes at least the best handling lens on a 1-series body ever made. It just fits right.
Nevermind the shift focus talk, it's not a big deal between 1,2 and 2,5. And this is where you use this lens. Be aware however, that the 50 L is very much softer closer than 3 ft than at some distance. So don't go shooting at mfd if you try this lens (as nearly 100% of the customers in my shop do when testing a lens)