Lavazza Maestro Ristretto (aluminum) is as good or better than most of the official Nespresso capsules. Highly recommend. They can be brewed as Ristretto, espresso, and Lungo. I rate them 9.5/10 :
Amazon.com: L'OR Espresso Capsules, 50 Count Ristretto, Single-Serve Aluminum Coffee Capsules Compatible with the L'OR BARISTA System & Nespresso Original Machines : Grocery & Gourmet Food