I would love an outlined system, ideally 5 people would work together and choose the best composition for the group, but this doesn't happen. Call order is just horrible because of locking certain champs and countering, those who do this deserve the frustration they get from the current system. Pick order is better than call for locking champs and countering, but it still lacks the team working together. Queue with a role would work if there were defined roles, but there are at least 2 or 3 extremely viable and perhaps better alternatives to the "Meta" depending on the opposing team and your team, so I don't know if you'd call lanes or what, but there aren't exactly 5 roles. Double Top is viable, Bruiser + ADC bot is viable, APC + ADC bot is viable, even single bot single top double mid can work but probably not solo/duo queue.
So how do we select roles if there aren't 5 roles to select? I guess we could have a build a team like WoW LFG, put our desired/capable roles and have someone invite you to their game, then build your own 5 man team that way, allowing the group to pick their composition. But none of this will do much, the only real answer is to role a 5 man premade, short of that I say pick order for lack of the other systems having a positive outcome.