I have a soft spot for Higgins of Duke Street.
Long before all these newcomers, back in the 60's and 70's, Mr and Mrs Higgins were selling brilliant coffees, hand grinders and the virtues of press pots and vacuum pots. Their Tanzanian Double A Chagga got me through my exams. They moved rather suddenly from South Molton St in the 80's and afterwards, you could see the odd frustrated ex-customer, sniffing the air in the street, wondering what had happened.
These days they look a bit expensive compared to upstarts like Steve and SMC and they've sort of missed the whole home espresso machine scene, http://www.hrhiggins.co.uk/ but Mrs Higgins is still there and knows the business like few others and if you go downstairs, will make you an excellent cup of coffee while the wife is in Selfridges.