Ask HN: What novel features would lend a new marketplace a competitive edge?

In the process of creating a new marketplace, I'm trying to think of novel features that would give the marketplace an advantage over existing ones.

One example I have considered is to be able to choose an arbitrary "basket" of services, and find the optimal set of providers of those services, for the customer's desired price and quality ranges.

I would greatly appreciate any other ideas!

Perhaps the following question will stir up your thinking: What annoyances have you experienced with online marketplaces, that could be fixed with novel features?

Thanks!