Out of every Linux distro I have used, Peppermint 7 was the absolute best one. I cannot even begin to describe how good that one is... Incredible interface and it's rock-solid!
I don't use Linux actively as my main OS for a myriad of reasons, but I can say that I had it on my computer for nearly 3 months, which is the longest time I ever had a Linux-based OS on my desktop (only OS - no dual-boot).
Zorin OS 12.4 Lite 64 bit is incredible, as well! Somewhat less stable than Peppermint, but it's still incredible. I love the start menu they have, as well... Very nice to look at. I have poor vision so a dark theme is a must... 12.4 Lite had an incredible dark theme with some nice icon color schemes.