Here's what I'd do for each kind of raid:
1) Progression Mythic raids: Loot council with clear rules ('we gear DPS first, then tanks, then healers and here's how we decide to move from one to the other')
2) Guild raids that have mixed attendance: EPGP with decay. You want to reward people for coming regularly, esp during the learning phases so that people who are there are rewarded and people who did the wiping and learning get some advantage over the folks who show up for farm. Decay, so you can't hoard things. Possibly a cap, too.
3) Casual raids with trusted friends/guildies where you end up pugging more than rarely: Roll, MS > OS. Loot assignment doesn't matter as much here by the nature of the raid. You can cap this so if someone has a lucky streak they don't take 4 pieces in a night (so, highest roll that hasn't won anything that night, for MS).
More than these is, to me, overthinking things.