My absolute favourite is Seattle's Best Dark Roast, which handily my in-laws can send me from Seattle every few months, as I've not been able to find it over here. Hopefully they can still get it when they move to Arizona in a few months.
For stuff I can get here I like Lavazza Espresso Roast for my espresso machine and some of the Asda Extra Special stuff for the French press is pretty good, again I usually like the darker roasts.
I'll be putting in an order from (local to me) Pure Roasters when I get paid next week, I've heard nothing but good things about them and I'm ,looking forward to trying their stuff.