I don't know about you but chain lube is one of those things that I never really know exactly when and how much to apply. Usually it's when my chain is actually super dry and squeaking. That's a bit too late. And which is the best type to use? There are like a million different types and brands.
I've personally settled on ProLink chain lube from recommendations from various folks including the awesome Bike Rack mechanics. I like the results but there are a lot of options and vary depending on your different factors.
To learn a bit more, here's an article from Full Cycle Bikes that discusses all about chain lube that you might find interesting.
If you are really interested, check out this testing that was done to check chain friction with ProLinkGold chain lube. VeloLab Revisited: Testing Chain Friction Over Time