I love 36' balloons.
My favorite by far is the TufTex 36. I am too afraid to neck them, but they get really big after a few inflations. So far none of my two Tuftex popped, but I think I am pushing my luck at this point.
The Belbal B350 is also great. If you like it firm and stable, this is the one. I used to like them more because of how durable they are, but they are just TOO firm for my taste. I still like them, especially for sitting on them. I am more confident around them than other balloons.
Cattex 36 is very affordable (where I live at least) and they hold up great. The material is soft and feels very nice, but their shape is a bit awkward in my opinion. Otherwise a good "starting point" for 36 balloons.
The Unique 36 is by far my biggest disappointment from all 36 inch balloons. They get barely to their size before I feel like they are popping and mine popped very early in two halves. On the other hand, it was fun playing with them when I under-inflated them, but for their price I think you can get better ones.
My experiences with the Qualatex 36 was good so far. They are the most round shape of all my 36 inch balloons, but have this weird, long neck that you can't inflate. The big upside is, that they have a variety of prints available. My favorite print is the Disney Princess one in pink and rose. They are also more expensive, sadly.
The SA 36 (from Tuky?) is amazing, IF you can get one of them at all. Great neck and soft material, nice shape in general. I only ever had one and sadly it got a small hole in the top, so I can't inflate it anymore. I live in Europe, so getting these (and the 24 version) seems impossible, sadly
I bought 3 Susy Card 36 balloons as well. They are "decent". They feel somewhat similar to the Qualatex balloons, are rather firm when inflated. They are the least interesting one I feel. I got them for 2€ per balloon, so I don't mind.
I want to get my hands on Sempertex balloons as well, but didn't find them with the colours that I want.
If you live in Europe, "big_balloons" on eBay also sell big balloons (shocking, I know). I recently ordered WXY 36 balloons and BWS/Rifco (32~) round balloons from them. Their prices are good and I got an immediate response from the owner about my order. I post an update if I have tried them.