Almost everything scuba right on my doorstep. All the PADI courses you could wish for, polite helpful staff, air fills, servicing, very active dive club and equipment sales. It's good to be able to go in and discuss things with someone who actually knows what they are talking about.
They will price match the Internet right there in the shop with no fuss.
Downside, they don't sell or service Suunto or Scubapro, so locally you have to go to either Sheffield or Leicester. I guess this is a good reason to buy something else.