First thing is that YOU DO NOT KEEP WHAT YOU DIG! Anyone who ascribes to that silly notion will not be digging with our crew. One fool tried it and was quickly and forcefully determined to not even think that way. His last dig with me involved me was around 15 yrs ago.
The coin flip works best for us. I prefer to dig with only one partner, but on rare occasions we have another along to complicate matters. The first pick continues on a regular rotation, but very valuable bottles are either bought out by one partner or sold and the profits split 50/50. This has worked for me and my buds for many years. No whining, no arguments, just diggin' fun. Heck, I could care less about most of the common stuff we dig anyway, so I let my partner take the majority of it. Yesterday's privies kicked out plenty of local pharmacy bottles, and stuff like Hostetter's, a few amber beers, sodas, and assorted patent meds. I took home exactly two pharmacies, he kept the rest. Two buckets full of bottles for him, two bottles for me, fair enough.