Looking on Make Up Alley reviews, all Armani brushes get 100% recommendations. And I concur - they are truly the best. By touch they are the softest, and being Armani, they look good too.
I didn't see the hype about the foundation brush until I went for a makeover, but since then, I've been converted. Not to say that the foundation didn't work well when I was just using fingers, but using the brush gave an unparalleled finish. You use less product, but it blends better and gets into all those difficult areas, like around the nose. It's really a wonder. Yes, it is expensive, but I've washed mine a lot and it's as good as new every time.
I also have a gift set of travel sized brushes, and I'm particularly impressed with the blusher brush (incredibly soft) and the concealer brush.
When you're in London, I'd recommend you buy Armani at Harvey Nichols, not Selfridges. They seem to be less interested in Selfridges and it's always 10x busier. My favourite SA at Harvey Nichols was a makeup artist in Hong Kong for 10 years (I think?) and he got me hooked, and knows exactly what to recommend me. Since then, I've never looked back.
I only have one lipstick, a red one which is incredible. Really rich and creamy - you can build up the colour and good staying power.