All right here we go. It doesn't matter what the game is (9-Ball or Ten Ball), the best players will win most of the time. Of course what helps even more is playing on tough equipment. Soft equipment is a bigger equalizer than playing with only nine balls.
Like Ironman said, there will be a luck factor in pool no matter what the game. But the skill factor far outweighs it. I love 9-Ball because the closer you get to winning, the closer you get to losing at the same time. You can make eight great shots and dog the nine, and you lose. I've seen it happen a million times. 9-Ball takes heart and courage to be a champion. That's why the top players win every tournament, without exception. A shortstop may get lucky and win a match or two, but he won't win the tournament.
My observation after nearly 40 years watching top flight pool is that the best players get there in the end. I don't care if it's a Race To Eleven or Race To Seven. Take a look at the past winners at DCC, and it's always been a Race To Seven. The shorter the race, the greater the pressure. Same goes for winner breaks or alternate breaks. The best player finds a way to win. On tough equipment, the cut break is not as effective. The head ball doesn't have to go every time, and even if it does, you don't have to run out.
All that being said, Ten Ball is about a 20% tougher game to play than 9-Ball. The break shot is harder and running out is tougher. It gives a little more advantage to the better player. In the modern era of pool, it probably is a better tournament game, with the skill level of today's players. Ten Ball, Race To Ten, D.E. and you'll find out who the best players are. Shortstops need not apply. JMHO