I love love LOVE Uniqlo
Mainly just because they seem to be literally the only high street store that uses a lot of cotton instead of polyester (looking at you, Gap) , their stuff washes well (also looking at you, Gap) and it's very very competitvely priced.
Much more stylish than similar-priced mid-range stores too. I mistakenly bought a stripey dress for about £45 from White Stuff last summer that I have always felt frumpy in. Bought a new one from Uniqlo for about £25 this summer and I feel about 20 years younger in it. Totally non-frumpy.
I love their leggings trousers and live in them. They do eventually sag after many many washes but they're so decently priced and last a pretty long time it doesn't matter. Again much longer-lasting than Gap and I like the fit of them even better than the bi-stretch (which are the only things I return to Gap for these days)
Nice plain T-shirts and camis.
Excellent Merino cardis, not the most thrilling items but I have three or four in various neutral colours and wear them all the time.
I haven't bought their cashmere so I don't know about that
I have a fab fab cotton navy lightweight summer trench that I have worn to death for the last two spring/summers.
Basically they get it right on style, quality, use of decent natural fabric and cost. I wear very few other brands these days.
Oh and I'm 40 and a size 12 if that helps, I need to be practically-dressed as I'm a working-from home mother but I hate to feel frumpy or saggy/baggy and honestly the only place I can guarantee will fit the bill is Uniqlo.