I've tried Kubuntu, Debian, Knoppix, DSL, Fedora, Ubuntu and Xubuntu (still on one laptop with XP as the other option).
They all have their good points - but for overall ease of use, availability of support, customization capability and functionality, I'm sticking with Ubuntu. It works great for a home computer. I'm not sure how practical it would be for a work computer if you need a VPN, and compatibility with Microsoft - Exchange, Office and servers. I might try that sometime to see.
I'm back to a single-boot machine for my primary computer, and have access to Windows for my iPhone and Pod on a backup hard drive or my old laptop.
Now that I've spent hours and hours getting my OS just the way I like it I'm going to see if I can do something with my computer (other than trying one of dozens of different desktop themes, icons or window borders - playing with wobbly windows, painting fire, rotating desktop cubes, dockys and all the other fun stuff you can do with Linux).
I'm not a purist when it comes to this kind of thing; I'll use whatever works best for me and whatever I like - right now that's Ubuntu. It would be fun to have a Mac to play with and when Windows 7 comes out I imagine I'll get a computer with that operating system on it.