Jay Leno had better ratings than David Letterman. Avatar drew more money than Black Panther. PC outsells Mac. Popularity doesn’t mean better. It never has, it never will.
So if a potential plan provider will tell you how big or popular they are, it doesn’t matter to you. At least it shouldn’t. The best plan providers can be the smallest because of their competency, not because of a creation of mergers and acquisitions.
For plan providers, you need the right fit for your plan’s needs, so don’t let plan provider size be a huge factor.