So my current lenses are 8-15 f/4 L, 24-70 f/2.8 II L, 50 f/1.4, 70-200 f/4 IS L, 100 f/2.8 L, with a 5D3.
I'm trying to decided between the 85L and the 24 TS-E for my next lens, which is a night and day decision. It will probably be my last (expensive) lens for a while. I shoot basically everything, including films. I'm trying to decide which lens will give me the more creative opportunity, but also fill some holes. The 24 will fill my landscape hole, while the 85 would fill my portrait hole. I wouldn't use the 24 conventionally though, and I would also love it for video because you can create really cool effects that can be used for dream sequences, etc. The 85 would be great for its amazing bokeh and low light performance.
I know none of you can objectively answer this question, but I'd love to hear some opinions anyway.