IMO the crux to getting more exciting competition is to reduce reliability. Reliability leads to predictability which means once a firm platform is established, one team can keep winning. The budget cap reduces reliability because you have to prioritize your resources more and you can't afford the same amount of people so you can't have one person dedicated to one part. I think capping how many people you can have on a team would help too. I like how in f2 there's fewer people per wheel on each pit stop. One person needs to take the wheel off and put the next wheel on. It's slower, but it's more exciting because it's less predictable how the pit stop will go.