I’ve tried many, many distros over the years and have settled now for Linux Mint (Cinammon 64bit).
I still dabble with different Desktop Environments – XFCE is always a lightweight favourite!
I see that KDE 5.0 is out for testing, might be worth a look – but I haven’t liked KDE since version 4 – personal preference.
Mint, however, serves me extremely well and with that Ubuntu base I get all the stability and compatibility.
Oh, and I’m a convert to the Chromebook! Linux based and a treat to use!