You can't compare the Wii to the PS4. The core problem with the Wii was different; it had one part covered (the sales) but lacked in other areas.
What defines the Playstation is God of War, Uncharted, Horizon Zero dawn, Bloodborne. Story driven third person action adventure games.
The Xbox is defined by Halo, Gears of War, FH and FM. First person, third person shooter, sim and arcade racers and they are some of the best in their class. Add to that a title like Sunset Overdrive.
Each console has it strengths, each has its weaknesses....and MS isnt doing as well because they messed up launch and had some weird strategy that deviated from what they did so well early last gen. So sales have never and will never define how good a console is.