They all give the same stat bonus, but the higher level ones have more durability. Since durability loss is a percentage, this doesn’t make them last any longer, they just cost more to repair.
suggestion is to make them all the same durability or actually have different stats
I’d like to see maybe a second low stat or maybe passive effect be added to higher lvl rings if what you say truly is the case. Though i can only go off what your saying as i just got rings at lvl 12 in desert.