For me the real star is Saunders Waterford, as it has an interesting surface texture combined with a truly robust nature, because it has been internally and externally sized. This can be an absolutely vital attribute if like me you make mistakes and need to sponge or scratch the paper to remove mistakes, or indeed, as a technique for creating certain effects.
St Cuthberts Mill produce the Saunders Waterford blocks containing their classic watercolour paper in convenient sizes for all three surface types, and they are ideal for painting while you travel, or if you don't like stretching paper. It's a great pleasure to work on really superb paper, so if you haven't tried Waterford you are in for a treat. Check out their website