which of the two is more accurate,
I'd say the mark 3 gets a slight nod here, but both will be more accurate than many shooters.
Single ten. Normally, revolvers take more time to clean in my experience, but the take down of the mark 3 is a pain.
Probably the single ten. I say probably as a good mark 3 can be very reliable. But, there is just not much that can go wrong with the single ten out of the box, so it would get the nod here.
I recently bought a used single ten. Buying the wolff spring replacements did wonders for the action, and I actually like it. As I have a hate-hate relationship with Ruger, that is a real compliment.