Vanguard vs Other Brokers for Index Funds

It seems like every post I've seen regarding investing in index funds has essentially used Vanguard as the default broker. Is there something specific about Vanguard that makes them better than say Fidelity or some other broker?

Currently all of the company's I've worked at have used Fidelity and I'm wondering whether there's an actual difference between Fidelity and Vanguard or if it would just be easier to do all my investing in one place.