I use a Mac fr most of this stuff, so there's really nothing decent I've ever tried to significantly replace anything of what iTunes does. However, because most of my music playback is actually done through Squeezebox products, I don't try to keep my iTunes library up to date.
WHat bothers me most about iTunes lately is its insistence on doing things like re-scanning artwork and checking something to do with gapless playback for every track. Kind of stinks when you drop a few thousand tracks into it. It takes a long time to scan to begin with. Aborting the next steps only leads to more frustration as it will attempt to do them when you drag music to the iPod.
I may tale a closer look at the links here in the post as well as any other alternatives for just quickly moving a few tracks to the iPod. Another thing iTunes doesn't do well is browse music on the iPod. The view is totally inconsistent with browsing your local music through iTunes.
But I have far bigger complaints about the iPods themselves. Unfortunately also a situation of being the best of the worst. I will say (again) that I think the Music app on the iPod touch (and iPhone) is a total and complete piece of crap from top to bottom. There's absolutely nothing good about that app at all. The designers and architects of that app should be ashamed of themselves and leave software development forever. I feel that strongly about it. My opinion about this is dropping every time Apple releases a software or product update. I think the new iPhone hardware is quite brilliant, but I really wish they'd go back to the drawing board on most of their built-in software. I just don't see them fixing the fundamental problems however. Most people either don't care or don't know any better (the Facebook crowd), so there's no impetus for Apple. They're still doing some things right, but people like John Gruber give them a lot more credit than they deserve in some instances.
Can you believe that after almost 9 years the iPod still doesn't support "Various Artists" compilation albums?