I'm a terrible shopper and tend to completely ignore all the shops which I don't consider "my shops" - this means I sometimes miss out on some great clothes but I'm a creature of habit.

Favourite brands (just clothes though I love quality and comfortable shoes and bags but am not a single-brand devotee):
Ralph Lauren (especially for polos, jumpers and casual shirts)
Gant (especially for jumpers and casual shirts)
DKNY (jeans)
Diesel (jeans)
Whistles (dresses, knitwear, tops)
Reiss (dresses, tops)
Joseph (for cashmere, knitwear and casual shirts)
Compotoir des Cottonniers (dresses, knitwear, tops)
Jack Wills (for pjs, casual shirts, jogging bottoms and hoodies - much better quality than A&F, IMO)
Gap (I wear their men's clothes

: cotton and cashmere jumpers, and white tshirts - love the longer loose fit of those)
Zara (for trendy pieces)
Brora (cashmere)
Coats and jackets are my investment pieces so I usually splurge on those or get them tailor made (jackets in particular). I also like Barbour.
Ehh, I wish we had J.Crew in Britain!