I voted washable.....but that is really our backup. All of ours go outside to potty - they have their own little yard off the patio. But we keep the doggy door closed at night and when we are not home....so them they have the washable pads down and they are great!
Just fyi.....I would recommend the washable pads from
www.piddlepads.com. We bought a dozen 2 1/2 years ago and most of those are still being used and in great shape. (The few that are no longer used were destroyed by my brother's daushaund (spelling) that chews up everything.)