You can use a meyer for jazz band too.

Nothing wrong with a YAS-23. That's a great starter horn. I know a few very good players who still play YAS and YTS-23's and love them. I'm not a huge fan of metal mouthpieces on alto, but I must say, the Otto Link New York metal mouthpieces sound really nice on the Yamaha's. The Jody Jazz hard rubber mouthpiece is a good one for alto. They have a nice crisp sound; bright but gutsy, not too shrill. The Ponzol mouthpieces are also very good for alto. I still think one of the best mouthpieces for the money is the Otto Link Tone Edge hard rubber mouthpieces. I would recommend something with a facing of at least a 5*, and would suggest a 6* and a 2.5 reed. I like LaVoz med. soft or mediums, Rico Jazz Select or Alexanders. The Vandoren ZZ reeds aren't too bad.

YAS-23's are good student horns and are certainly far better than some Chinese made piece of crap that tries to pass itself off as a pro horn. I always recommend the Meyer 5M, as it is a good all-around mouhpiece. You can play several styles with it. I also like using LaVoz medium reeds. Of course, that is something you would have to experiment with and see for yourself. With so many choices, it's hard to always know what to use, but time and experience, as well as guidance from more experienced players will always help.