I have the 3/8 fuel, whatever the most badass 3/8 one they have... Like 180 bare tool I think it was? It's awesome and I love it. My m18 impact driver 1/4 hex I got in 2012 and have beat the shit it of it and it won't die.
Also got the fuel saw zall and a couple drills. And the weed whacker. It's all been awesome. My neighbor has the chainsaw and even that is damn good.