Agree about the Mothercare t shirt ones, the double layer is useless! Unfortunately I'd already de-tagged it and worn it by the time I realised...
I love the ones I bought from Mamaway.co.uk - several different styles and really don't look like nursing tops. I also have a few from H&M that are good. I never managed the vest down thingy, and I like to have a warm tummy in winter, so I wear one every day now.
HTH