Honestly, they're all basically the same. Over a period of a few weeks and given a consistant player base, most of the loot will go to the same people. That's anything, from loot council to pure DKP bidding. It'll all come out in the wash, and the same people end up with pretty much the same loot.
Given that, you should look for the loot system that will cause the least guild drama. The goal can't be fairness, because they all end up in roughly the same place. Instead, look for the one that makes the raiding players the most comfortable.
On a personal note, I've done every loot system under the sun. I've hade pure loot councils, and loot councils with rules for "fairness". I've done DKP fixed cost, and pure DKP auctions. I've even done pure random. I prefer DKP, because the rules moderate the guild drama. Instead of the occasional flareup over an award leading to major drama, you get a lot of low-level grumbling and suggested tweaking for the DKP system. Same amount of drama, but a low, steady stream instead of random explosions.