For me, this is easy, and thus illustrative of why these polls are often not very useful [no offense is intended by that; they're still fun, but they are limited]. I am a long-time Mac fan , but an even longer-time multi-platform user . I use a PC and a Mac every day. I've built my own PCs, my own "Hackintoshes," and quite a few amps, pre-amps, and speaker systems. But all my music is stored on my Macs. At home, our network has 1.2TB of music & video on the local network. All stored, shared, and played on Macs. Every car has an iPod hard-wired in. My wife and oldest daughter each have an iPhone and iPod, as do I. We have multiple iPod players, like iHome and Griffin units. We even have an Apple Hi-Fi in the garage [where it belongs]. So, given the horrendous support for the platform by so many of the other devices, and the relatively mediocre or barely acceptable support provided by those that actually make some effort, the choice of platform becomes almost a no-brainer.
I know there are many WinPC & Linux enthusiasts who--on the positive side--like the flexibility of FLAC and other aspects of wider ranging codec and platform choices, and who--on the slightly less positive side--decry iTunes on non-Mac platforms [and there is no question it is nowhere near what it is on the Mac platform]. And there are plenty of Mac enthusiasts who prefer other music management solutions over iTunes. I am not one of them. I personally love iTunes. I buy DRM-free tracks from the iT store, and I rip CDs using Apple's lossless codec, which is pretty good. And for integration with the platform, it is impossible to beat the iPod portion of the ecosystem. And if you have more than one iPod/iPhone, as our family does, then there really is a self-reinforcing effect. And as the home "sysadmin," I am glad it's on all one platform [of course, two of our Macs have Fusion and XP loaded on them.]
I have no doubt that, in any given generation of electronics, there are iPods that are bested by, and better than, other players. For example, the 5/5.5G iPod is well-regarded because of its Wolfson DAC. Others are less well-regarded. But all are more than adequate for their basic task of playing 128-256k files. If you rip lossless, then you might listen a little closer. But if you are like me, you listen to your better cans through a headamp also. So, the post-DAC analog stages become less important.
For some people, this turns into a features debate. If you want FM built-in, and you don't want an add-in accessory like the iPod has, then your choice is probably not an iPod. If you want removable storage, built-in laser pointer, flash camera, same thing.
But for me, my music has gotten so integrated with my platform choice--Mac OS X--that it's almost like the choice of hardware is secondary. If the iPods did not integrate well, it might be different. But they integrate superbly.
Just my over-inflated $.02. Cheers!