Best oracle algorithms?

A lot of the coins being released require a successful oracle algorithm in order to be successful. I had two questions about this. First, what do you think the best oracle algorithms out there are and why? Who is thinking about this in the smartest way that you've seen? Second, what do you think the most important past work / literature is on oracle algorithms that are byzantine fault tolerant?

To be clear to everyone, by "oracle" I mean a Byzantine-fault tolerant system for creating agreement about "real" events that have occurred outside of the blockchain. For example, all stable-coins require a fault-tolerant oracle to tell the system what the right value is to peg your currency to (e.g., the system needs to "know" what the value of USD is in a decentralized, trust-less way or it can't work). All prediction markets have to have a oracle system (e.g., if you create a prediction market for "Donald Trump wins election" then you need a decentralized, trust-less way of ensuring that the contracts "know" who actually won).