I find Brick Lane a bit over-run, and as a consequence standards have slipped . Tooting is an excellent area to head for, so are Southall and Wembey.
If you want somewhere central, try Chowki on Denham Street just behind Piccadilly Circus. Some interesting regional dishes at very friendly prices. To try some very authentic South India vegetarian cooking, Woodland's on Marylebone Lane is a favourite.