TL;DR:
+ no income share for players with metal>=500
+ no reclaim share (current)
? 5% private mex income (current)
? no other units' income share (current)
+ no OD investment payback
+ better energy share before team ODSprung's, actually @knorke's idea is generally good. Still it would not be the best overall ressource distribution yet.
AFAIK currently metal extractors' income is 95% shared and 5% private. If a player has metal income that exceeds his storage, his metal net income contributes to the shared metal income while he is excluded from shared income (Is this currently really correctly implemented?). If a player's energy net income (=sum of the players units' energy rates) is positive, it is used for team overdrive as much as possible and overdrive metal is shared proportionally to the players' overdrive energy investment among the players whos metal storage is not full (not sure about the proportionality, but if it was so, then high energy investment would be rewarded, but not good linking).
What if all team members have >500 metal stored? Then the income should be distributed among those who don't have full storage instead of nobody getting income share. Imo there should be storage states of players: 1. metal<500, 2. metal>=500 but not full, 3. metal=metal storage.
All mexes' metal income (or 95% of it) and overdrive except reclaim should be shared equally among the players of the best state. Of course the discretization of states is a bit arbitrary, but easy to understand. Additionally people of state 3 would also give the rest of their metal net income (reclaim + other units' incomes like coms, facs, cons...) to the players of the best state.
Generally the only argument for any kind of share reduction, for example no reclaim share, 5% private mex income, no other units' income share, OD investment payback,..., that comes to my mind, is preventing waste/rewarding good play. But OD investment payback rewards noobs for spamming fusions even though only connected to 1 mex. Excluding reclaim from share on the other hand rewards good play, while it keeps the only purpose of storage. Current 5% mex metal income private share also rewards good play. 5% private share and not sharing reclaim only causes uneven income in no noob games though.
Excluding other units' incomes from shared income is actually arbitrary. Even if their income is meant to keep their building ability without other income, this is not an argument to exclude them from sharing. The best reason to not share other units' income is propably 2nd coms for uneven teams. If the 2 coms player didn't get both coms' income, income would be very imbalanced within the smaller team. Not sharing coms' income also punishes com loss. But should other units than mexes/coms' income not be shared? Those other units' income is correlated to a player's BP, so not forcing him to share it seems reasonable. However it rewards nano spam a bit even though not enough res for BP..
AFAIK energy is currently not shared, but energy excess only used for OD. So when my enegy production is destroyed, I still get metal share, but have not enough energy to spend it. Also if I have a well connected energy production, but need the energy for building already, and another player has badly connected energy production with energy excess, it would be better if his energy excess would power my building while my energy excess is used for OD, where the other player would get his share from, too. (Of course only connected energy can be used for OD, but any energy for building.) In no noob games it would be good if all players' energy gross income rate would be shared equally. (But while a player has at least his energy reserve, his shared energy income rate should be limited to his energy need while the rest is used for OD and if there is still excess, the rest distributed to the emptiest player storages first. Maybe even do automatic transfer of stored energy additionally to OD.) The problem would be that bad players could drain the team's energy by building without own energy production or by spamming cloaking field. So good players would have to build energy productions to also power bad players who don't build power plants by themselves, instead of bad players being punished for not having energy productions. So the best solution for mixed skill games would be that every player uses his energy for own units first. Excess is then given to players with energy deficit first giving all players with energy=0 equal energy rate, then filling energy reserve of lowest player storage first (maybe the minimum of player reserve and 200 instead), and only the rest goes to OD. While the players' energy rates calculated by those principles except OD are held constant, the teams' remaining energy rate would have to be redistributed to all power plants for ideal OD, no matter who owns them.
And of course afk or resigning players should give all their res to the team (/players with best state) (not sure if implemented yet).