What is the best mouthpiece?
I believe the best mouthpieces for beginners and intermediate are Yamaha (standard) or Vandoren. Once you get to know a bit more about your set-up however it might be worth trying some vintage mouthpieces, especially if you use a vintage saxophone. The old (pre 1975) Otto Links for tenor, Selmer Soloist and New York Meyers for alto are much better than the modern ones IMO. It is also worth considering a custom mouthpiece: RPC (US) and Ed Pillinger(UK) are extremely good and not as outrageously expensive as some.