recommendations for collapsible bottle

I have had good luck with Platypus bottles. There are several models that have a clip. I would suggest finding one that has a screw on cap (not a push/pull cap) as they are less prone to leaking.

Vapurs are fine, at least no leaks or problems in several years' use. Roll-up-able plastic with carabiners & both screw-off & pull-up caps. Sometimes awkward when only part full - pliant equals squooshy.

I have Playtpus also. You can buy alternate tops, but I haven't had problems with the pull/push mouth piece. . Same partly full problem as with Vapors.
Somewhere I also found a collar that clipped to a bottle neck. it had a caribiner attached for what you want. However, it was sometimes big for the smaller bottles. For storage, I like the simple no attachment bottles with the collar to attach or not.
I started using rigid bottles that were smaller and fit into my purse better, but have forgotten too many on the planes. Going back to my Platypus.

I've been through a couple of Vapurs. Each lasted about three years. I just got a HyrdaPak. The material is a little sturdier than a Vapur, but it is top-heavy so you need to be careful with it on table tops, tray tables, etc.

Thank you all very much. I had not heard of Vapurs, but had the others, so thank you all very much for the recommendations- have a medical issue that needs constant hydration.

One of my worst travel days was the one when I realized I'd left my Platypus in the refrigerator of our apartment!