I'm glad someone brought back this older post, I must have missed it. When I switched to full-frame/mirrorless, I made the decision to only get high quality glass with no compromises. That didn't necessarily mean getting the widest aperture lenses, but I wanted to ensure that anything lacking in my photography wasn't due to cutting corners on gear.
Rarely do I shoot wide open, especially on portrait work
I wholeheartedly agree with this. Most of my portrait work starts at f/8 and is adjusted from there, based on the desired DoF. Last year I collaborated with a natural light family photographer and we were both amused at the differences in our approaches. I shot headshots in a studio environment at f/8 and smaller, and she somehow got the entire family in focus at f/1.4.
I have an old Pentax legacy 135mm f/1.8 that beats out everything in the bag on OOF
That is hands-down my favorite focal length. I learned to shoot portraits on an APS-C body with an 85mm lens, and now 135mm just feels like the sweet spot. It's not always the right lens, but when it is I love the results.
This is the main reason I use an almost-2lb 24-70 instead of a 6oz 40mm plastic prime. Again, I don't always need the wider aperture, but the better build and image quality are where it's at.
85mm is a good focal length for portraits, but I have a choice of zooms that cover that focal range
I made the same choice, but the other way around. I've had an 85mm and 135mm in my bag for a few years now, and just picked up a large heavy 70-200 f/2.8 this year for sports. The guys at the camera shop joked that I'd be back in a few weeks to sell them my 85 and 135 now that I had a large fast zoom that covered that range, but that never happened. For sports, the 70-200 is unrivaled - that's what it was designed for. But for portrait work, such a large heavy lens is just unwieldy, and I still prefer the relatively smaller and lighter primes. Technically the 135mm is neither small nor light, but I refuse to give it up.