I've quite stuffed with Ubuntu.
But each time I try other distro, I felt more depressed. Ubuntu is relitively easier, although it can't really make me feel satisfied.
There are bunch of Ubuntu branches, I tried some of them but they don't really made me happier either. I also tried LXDE+Ubuntu and openSUSE with KDE4. They don't make me happier either.
Do we have other options? I know Chrome OS will be released next year, but it's quite a long time. Some people recommended Arch Linux or Linux Mint. Anyway, it's not important what OS you used, but it's important what you do with the OS and how you feel when you are using the OS.