The shop in Hatfields has been my favourite for a long time - excellent service.
Evans are happy to sell bikes but after that they lose interest eg their repairs/servicing waiting list is weeks long - I would have thought there was money to be made, but as they never have enough staff to bring down the waiting time, Evans obviously don't bother.
As an aside, I popped into the bike shop on Jamaica Road and the guy there did three puncture repairs in quick succession and got good tips (30%) from all three unconnected punters.
The London Bicycle Repair shop on Hatfields and also the hire at Gabriels Wharf are excellent. I bought my bike there a few weeks ago to replace a stolen one and they were really helpful and provided me with tons of advice. I had a small problem with the gears a few days after getting the bike and it was fixed within minutes! They're well worth visiting.
OYB are good for sales, including ordering out-of-stock models and pre-delivery checks, but I have not enjoyed great after-sales service from them.
Condor have always been excellent for service and support, always take the time to talk you through things. Try and go at off-peak times, though, as the corollary of the individual service ethic is that you'll have quite a wait if there are more than one or two other people ahead of you.
My experience of the recycling bike shop at the back of the E&C was very different. I don't agree although it may be that they just treat women appallingly. I asked for two spokes to be replaced in the wheel of my last bike - the guy quoted me £35 and then tried to tell me it was not worth doing the job. He then tried to push me into buying a rubbish old bike in a much worse state than mine. Mine was a six month old folder and the only problem was that I had hit a pot-hole.The one he tried to flog me was a clapped out old rusty folder at least twenty years old. When I demurred he then got threatening. I was alone in the shop at the time and though not easily cowed it was an intimidating experience. In fact I wrote and complained about it to the London Cycling Campaign. This was about 18 months ago and it may be that there have been staff changes since then and I would not want to do down anyone unfairly. Definitely a case however, of "Buyer beware".