I’ve heard of Sansa, they seem to be doing pretty well in the MP3 player market. I used to buy Creative players until I got sick of them launching a new model every five minutes and abandoning support for the previous one. I don’t think they do that so much nowadays, but I’ll stick with what I trust.
One big reason I don’t like newer iPods is because of the volume cap. It makes them too quiet and I have to run them through a booster. I’ve also heard the audio quality on the flash-based models isn’t great – my 5th Gen sounds a world better than my 3rd Gen Nano.