Pol Roger is one of the best non-vintage Champagnes and very fairly priced compared to most. In fact if you ask most people who work in wine for their favourite Grande Marque, they're almost bound to say Pol Roger. And that includes us.
Pol Roger's Brut Réserve is a traditional favourite in the U.K in particular (it was Winston Churchill's choice). The wine is aged in its bottle for an extended period and is better than many (more expensive) vintage Champagnes.