I reckon all the OM shopping partners are great, mainly because I am a shameless pragmatist... Seriously though, since we started the site, all the major retailers have made marked improvements to their sites. The latest Cotswold changes are interesting though, because they've tried to make it much quicker to reach the product you might want to buy without having to go through loads of intermediate steps.
Ironically though, I don't buy much outdoor gear these days, so I'm not a particularly good person to comment. I do get quite a few mountain bike spares online though and reckon then latest Chain Reaction incarnation is as good as anything with stonking delivery and stock information available when you order.
A propos of Blacks, remember it's .co.uk, on no account try .com, you may be surprised... Oh, especially if you're at work. Someone was a bit slow registering their domain name I reckon.