Get the 135L first and it's the start of a long and enduring love affair. It's my favorite lens. I got both the Sigmas you mention, and the 35 is great, and the 85 will also be great, .... until you try the 1.2 Sure it is slower (the fastest is actually the 1.8, then Sigma 1.4, and then the 1.2), but there is something about the dreamy IQ of the 1.2 that keeps you wanting it badly. I saw someone suggested the 100L here. Great lens, but imo the AF is a bit too slow for action portraits.
Just my two cents.
Way back when I had a Canon 30D, I tried the 135L. It was amazing—definitely one of the most impressive lenses (if not the most) I've ever used. But I don't think I've ever tried a 135mm on full frame, and I don't even have a zoom in that range, so I probably should give it a shot.
It's even great with the 2xIII TC