Personally I don't like strong roast coffees. I'd rather have a medium roast and make it stronger if necessary.
By far my favourite is Kenyan (often labelled Kenyan AA). I used to buy it in Whittards until they stopped doing it (they still do Kenya Peaberry, which is also nice, but not quite as good).
Now I buy Sainsbury's fairtrade Kenyan - they do it in both beans and ground. I think the beans are a cream/orange coloured packet. Good value and tastes great - I prefer it to Jamaican Blue Mountain (which is also mild roast, but rather expensive). If you want something strong and "smoky" try Old Brown Java.
I keep my beans in the freezer and ground direct from frozen - they keep much, much better that way and seem to brew just as well.