This depends on the type of instrument you're looking for, as well as the amount of money you're willing to spend on the instrument. For general school use, there isn't anything wrong with Yamaha. They're quite good.
Remember, this is just my opinion. You should always research an instrument in depth before you purchase one. Ideally, you should be able to play the instrument before you buy it.
For Saxophones, you can't go wrong with Selmer. I play a Bundy II (made by Selmer), and it works very well. It is a student level instrument. Here is the Selmer website:
http://www.selmer.com/For Clarinets, I'd recommend Buffet, hands down. Here is the website:
http://www.buffet-crampon.com/I'll try to post more later.