I have both the 135/2 and the 85/1.2, which I use for people, primarily indoors. I keep thinking I prefer the 135, but guess what, when I do the final edit, it's about 70-30 in favour of the 85mm. It's that good. I have a 1.3x crop body, so it's still a great portrait length.
Always buy second-hand if you can, but you will find that the 85s (of any aperture) come up rarely, and the 135 even less frequently than that, which is another way of saying that they're great lenses that people find difficult to part with.
I don't find the 85/1.2 to be slow to AF in real world usage. OK so it's clearly not as fast as the 135 or the 200/2.8, but it is perfectly useable in all circumstances I have come across to date.