I go for either Lavazza, or Java-Sumatra from Lidl. For the price they can't be beat!
Cook it in a Bialetti Moka over a trangia, primus or campfire.
Recently got an old enamel Finel percolator from a charity shop, not the strongest tasting coffee comes out of it but fun to watch it bubbling away.
If its not strong enough in the perkie let it brew longer its still one of my favourite ways to brew