My all time favorite is Windows 2000 for 2 reasons:
1. It has a little media preview panel when I'm looking through my video or audio files. I don't have to open media player to be reminded which song or video this one is. I just select it & press play in the side panel.
2. When I want to open a CD/DVD with different kinds of files, Win2k doesn't stop to ask me "What do you want Windows to do?", (Use Windows Media Player, Nero Player, VLC player, copy pictures to folder on my computer, view a slideshow, print pictures, Open folder to view files, etc.,) It just opens it and lists everything. How hard is that?
XP is just more annoying than Win2k, but I've learned to put up with it since Win2k is no longer supported. I'd try Linux, but I hear it's not the best for surfing the internet due a lack of some needed plug-ins.