When you're choosing a loot system for your guild, consider every available option. The system you choose should meet all of the following requirements.
Your officers are willing to enforce the system.
Your members agree to follow the system.
The system does not cause excessive drama.
The system does not put an undue burden on the officers' time.
The system is fair.
That last one is really the kicker. Fair is a matter of perspective. Is it fair for someone who's been in your guild longer to have loot priority over a newer member? Is it fair for a player who hasn't raided as much to win an item, purely by luck, over someone who has attended every run? You can grapple endlessly with questions like these.
A fair system, by my definition, ...