I need to be able to pick 2 options.
I run 4E and may switch to Essentials only, simply because I prefer a more "basic" game- The Rules Compendium, Heros of the Fallen lands, and the Monster Kit will likely provide all I need (plus I have my MM1/2)
And I play Swords & Wizardry WB/LBB as well as MCM D&D (which has influenced my 4E "basic" game as well)