When picking a retirement plan provider whether it’s a third party administrator (TPA) or financial advisor, don’t pick a provider just because they’re the biggest provider out there. Bigger doesn’t mean better. As you see in high school, being popular also doesn’t mean better either.
You should pick a TPA that is competent at what they do and that charges a reasonable fee. The number of plans under management or/administration may mean the provider is very good at generating business, but it doesn’t mean they’re good at what they do.
When someone says their TPA is better because all the plans they administer, all I point out is that Bud Light is the best selling beer in the United States. Does that make it the best beer? Of course not. Case closed.