If we're talking 'franchise' as opposed to 'series' then I would say Mario stomps all over Zelda. Besides the Super Mario Bros. series, you have the Mario Kart, Mario Party, Super Smash Bros., Mario RPG, Mario Tennis, and Mario Golf games.
If we're talking about series, then I would say Legend of Zelda > Super Mario Bros.
1. Zelda
2. Mario
3. Metroid
If we're talking about series, then I would say Legend of Zelda > Super Mario Bros.
1. Zelda
2. Mario
3. Metroid