I'd start out with a 2oz squeeze bottle of anything. Yes, anything. And apply it when needed but more importantly wipe off excess after oiling and riding a day. When the bottle was empty I'd fill it with whatever was in the bottom of empty qt. containers in gas stations.

The dry lubes will let your chain rust in a days worth of heavy rain and the oily lubes will collect dirt. The important part is wiping off the extra so it doesn't collect dirt. I'd be inclined to go with a wet lube if there's regular rain and just be scrupulous with wiping extra off.