Personally I bought a few COS items in the last year and I am disappointed with the quality. (Sorry COS fans.) My clothes are a mixture of Burberry, MaxMara, Chanel, DVF, Joseph on the higher end; some knits from mid-range such as Pure Collection, Hobbs, Borden, Jigsaw, All Saints; lower end I have quite a bit from Uniqlo from before and bought 2 jackets from Zara in 10 years. Again the quality of Uniqlo and Zara is in serious decline so I don't think I will buy more from them.
I try to avoid too much patterns unless it's Hermes of course.
I agree with you regarding declining quality of Cos and Uniqlo.