Digital BW, The Print

My favourite papers so far, for colour saturation, d-max, and detail, are, in this order: 
- Epson Exhibition Fibre (called Traditional in some territories) (you said price did not matter!)
- Hahnemuhle Fine Art Baryta (too much sparkle in the texture, but the colour is great!)
- Innova Fibre Semi-matte
- Ilford Galerie Gold Silk Fibre (if you take price into account, this goes near the top)

As for matte papers, there are some nice ones, but they don't have the colour saturation that I want.