I think it would be exactly like that, because that's how it already works for relays. The Tor Project operates a measurement system that tests relays in various ways and records their status in the public consensus document. Clients then use weighted random selection (along with some screening criteria) to choose relays in proportion to how much bandwidth they provide, according to the consensus.

Having something like that turned on by default but being able to disable it would be a good choice.

Ultimately until someone can satisfy a user’s concern about the privacy and security of what flows through their connection there will be scrutiny on this piece. Being able to interject one’s own proxy or vpn tunnel could be interesting.

Right, I think that it could be good. But it's not obvious that it would be good while it would definitely add complexity, bugs, and attack surface, and discourage at least some people from using Tor.

> Being able to interject one’s own proxy... could be interesting.

I think this is essentially what the Tor Project wants to see instead: if you're in a position to do so, operate your own relay and make it your entry guard. That adds capacity for the network and helps you by mitigating the risk of connecting to a malicious guard.

I feel it would be a good choice to give users rather than force all users into it. Not all users stories are the same.

You’re right as well as this is one way it could be, and there could be other ways.

Tor might want to see that, but I’m not entirely sure how well it’s going when hosting exit relays can be an issue for the hoster.