There have been some interesting articles in recent years on various chain lubes' ability to reduce drag.
This test conducted by Friction Facts (https://www.friction-facts.com/) claims that soaking a chain in melted paraffin reduces friction better than any commercial lube: https://www.scribd.com/doc/262044061/Velo-Friction-Facts-Chain-Lube-Efficiency-Tests
NOTE: If you decide to try the melted paraffin route, be VERY careful about melting the paraffin with a double boiler as paraffin can and DOES catch fire if heated to a high enough temperature. Ask me how I know. Anyhow, here are some directions for safely melting paraffin: http://www.candletech.com/candle-making/wax-melting-instructions/
Here's another review (http://biketestreviews.com/the-last-word-on-chain-lubrication/)that acknowledges that paraffin does indeed produce low friction for chains but not running a paraffin wax lubed chain in a straight line tends to shear the paraffin wax out from between the plates, pins and rollers fairly quickly so that all “lubrication” is gone, whereas a wet-lube will flow back into the chain once load and deflection have eased.
From my experience, I would agree with this assessment of paraffin especially for use in wet weather. It works great for a short amount of time, but requires extensive work frequently to resoak a chain in paraffin as paraffin lubed chains tend to get noisy pretty quickly. In terms of bike maintenance, I'm kind of a set-it-and-forget-it type of guy so using paraffin was far too fussy for me along with paraffin lubed chains easily getting rusty in wet weather.
I'm planning an upcoming test of chain lubes with a focus on durability. As chains on mountain bikes are subject to conditions that are often less than ideal (dirt, dust, water, etc.), my thought is that the durability of a chain lube is far more important than the absolute amount of friction reduction that it provides. Having the longest relube interval before a chain gets noisy might be one of the most important considerations for me.
In addition to what I think might be the two lubes with some of the best real-world effectiveness, perhaps adding motor oil might be also be a good inclusion to see if relatively cheap motor oil is a good substitute to far more expensive bike lube.
Thoughts? Interested in participating in the tests? Email me at firstname.lastname@example.org.