Interesting thread OP!
I mostly buy:
Uniqlo (their knitwear and jeggings)
Hush (various bits and bobs, some of it is the most used stuff in my wardrobe now I think about it esp leggings, chinos and their khaki jacket)
Warehouse (dresses and skirts particularly good and nice basic tops)
Monsoon occasionally (I have a dress from there I wear all the time and it's not at all Monsoon-y!)
Esprit is great for tops I find
H&M for tops/knits and Zara occasionally.
John Lewis and Partners new stuff can be good, I have a great coat from them and their shirts are nice
In the sale I buy Whistles dresses (the Lola shirt dress) and tops.
If I had more spare cash like in the odlen days before I DC I would still buy the above but would also buy more Jigsaw, By Malene Birger, a bit of Toast, even the occasional bit of Joseph though the prices used to make my eyes water.
I'm trying to buy less and WELL, a bit to save money but also because I'm thinking about sustainability where I can and I do have a wardrobe full of perfectly nice clothes! This A/W for example I just bought a Hush skirt and leggings, a Warehouse skirt and 2 tops, an H&M sweater and new trainers (Geox). All my other Uniqlo knits, my jackets and coats, even last years' and the year before's boots - all still in great nick so I'm not replacing them. (and fashion is one of my major vices so this is a big step for me!)