Seeing as you ask, Peeps...
Dub Vendor (Clapham Junction), I used to visit a few times a year when in London on business. They were always very helpful and friendly, gave me a discount without me haggling, stuck me on their mailing list and even gave me a few freebies once. Sadly I now have to pay my own £147 or whatever it is to go down to the smoke by rail, and they stopped mailing me their lists very soon after they started sending them.
Greensleeeves I've had no direct dealings with, but didn't they wipe 7" and 12" singles from their catalogue many years ago? And record store owners tell me they're lovely people too, but not the most organised you're likely to find (eg order in February, chase up in April, maybe they'll find what you wanted in a bin in August).
With Ernie's I order at 11pm (GMT) on Monday evening and the parcel arrives by lunchtime on Wednesday; not bad for an Atlantic crossing. The 30% post/tax is a bit of a bind after paying a flat $19 for so long, but with 7" singles at $2.99 compared with £3.50/£3.99 in the UK, it's still worthwhile. Similarly with LPs ($9.99 vs £10.99).
..and the part of Yorkshire I've moved to is Sheffield; a nice city in many respects but not one to go shopping for music. A couple of people have asked me where to go here, but I just tell them to spend their first ten quid or so on a ticket to Leeds or Manchester and spend the rest of their cash there.