It really depends on your needs and requirements - the "best" for me was a player with a price tag at approx. $70. I didn't buy it because of the price, but because of the various features it has.
buy a Zen, best I ever had. Just recently bought the newest generation (8GB), superb sound, design and the battery last quite long. I had the Zen Mirco before, used it for 9month every day in a rattling old Mercedes Bus.
Go and look at them, they all do pretty much the same job there's no point buying the most expensive one based on its feature list (most of which you'll never use). In the end I couldn't help but get an iPod Nano, as much as I would have preferred to get something slightly different everything else just had that cheap and tacky Chinese feel to them and were clearly 'styled' with lots of blue lights and black to entertain computer modding geeks.
It depends on how much memory and how many features you want really.
I've got an ipod classic 80gb and it's brilliant, far better than i was expecting because i have always gone for Sony hard drive mp3 players (because i was never a fan of the old ipods) but there was not one that was offering more than 8gb memory at the time when i needed a new one.
The only complaints about the ipod classic i have is that the shiny back scratches far too easily and the headphones it comes with are very poor (sound quality and confort in your ear) but both of these can sorted quickly.