Grats on a successful feeding for starters! It's always nice when they eat.
As for fresh killed or stunned, fresh killed is just as good a f/t however you never want to put a stunned mouse/rat in with any reptile. You never know when it will come out of that state and it will panic. It will cause it to be much more aggressive and bitey than if you just put a happy, healthy live mouse/rat in there.