This is part of what I do for a living as a textile engineer, so it's not random BS.
There are mil-spec standards for many types of webbing. Standard 2" nylon webbing we use for scuba will have a tensile strength of roughly 4500lbs. This will depend on the quality of the nylon, how well it has been impregnated with the resin, etc etc. but generally speaking it's around 2 tonnes. Any of the cheaper stuff will be more than strong enough.
That said, the cheaper stuff will not have the same color fastness. Nylon breaks down rapidly in chlorine and sunlight, and the cheaper webbings will typically fade quite a bit faster.
If it's too flimsy, it will curl when under tension and becomes very uncomfortable to wear which is why we use the stiffened webbing instead of say seatbelt webbing.
It may not have the same abrasion resistance either which will determine longevity if you are adjusting it regularly.
Most of this doesn't really matter in the grand scheme of things for our application, but if you are doing a lot of work in pools or the gear spends a lot of time in the sun, you should try to find stiffened polyester webbing which will not break down nearly as rapidly.