I have been using Putoline chain wax on the solos and tandem since christmas. This is a solid graphited wax that you heat on the stove
So far it appears to be by far the best lube I have used. It is lasting hundreds of miles even used in wet and muddy conditions ( although I have not ridden a huge amount in mud recently)
It is a faff to apply - but to some extent that is compensated for by the fact you don't have to clean the chain - just dump it into the can of molten wax.
Measuring the chains they don't appear to be wearing any quicker than using conventional lube. The wax does not get stripped out by peaty / muddy stuff unlike liquid lubes, dirt does not get stuck to it as it is not sticky on the surface in the same way. each application lasts maybe 3 x as long as conventional lubes. It is under £20 a kilo.
Disadvantages - the lube itself is really manky - and does not wash off hands or clothes easily
I have previously used finishline green and purple extreme.
Needs to be used thru the winter to be sure of the advantages but so far I am convinced