Threadless is noticeably more rigid to me. Lighter and stiffer. I prefer it by a large margin. Most threadless stems are ugly, but they don't have to be.

Quills were good enough in the old days. You still are not going to get dropped if you have a quill stem. Obvious advantages are up/down adjustability, sleek look, and easy to align. Steer tubes can sometimes bulge from both corrosion and normal preload IME - in spite of prevailing wisdom. Sliced wedge stem design is superior to the Cinelli conical wedges IMO.

AFA handlebars - I went to 31.8 accidentally on my new bike, because the only bar I found with the bend I wanted in silver only came in 31.8. I'm glad, as it's really nice when climbing, and I'm surrounded by hills. I didn't realize how much my old stem/bars flexed till I got this.