I like fences.
There are pros and cons to both situations.
In one case, you have one dominant game driving the market, and providing a template for others to follow, or differenciate themselves from. That's the paradigm we have had for the longest time in RPG history with D&D. If the leader goes down, it could take the whole "industry" along with it. There is a state of monopoly, and if you're a believer in capitalism and competition, that's not really a good thing. One game has it all, and it follows that more exposition flows from there for that single publisher.
In the other case, there is a a plethora of different games, and no clear leader. There is no leader to try to copy or differenciate yourself from, so it might lead to more diversity, and more innovation, and yet, without the benefit of a master template to follow, or not. After all, competition drives the market and no monopoly means more competition in terms not only of forms, production values and prices, but ideas also. If one of the competitors goes down, it doesn't take the whole "industry" with it. No one is "too big to fail".
Really, I would slightly lean towards the "no leader" situation, since I believe in a capitalism of ideas, but there really are pros and cons to both situations.