Roy, but Walker is underrated in his own right. Roy is mostly quietly effective, a shutdown D who isn't particularly excellent at any one thing with some underrated offensive instincts and a pretty hard, quick shot. Walker is a bit more of a puck lugger and offensive mover, more agile skater, sneakier wrister, and imo a little more versatile. But on this year alone, Roy would be a complementary #2-#3, Walker more of a #4-5 imho.
That being said Walker had a stint next to Doughty playing 20+ minutes and looked really good doing that too, so next year is huge for both guys cementing who they are with consistency.