I'm looking for some suggestions on how to issue and tally the voting of potential product or system features for multiple stake-holders.

One idea is to have voters issue simple school-like letter grades: A, B, C, D, F, along with + and -.

Another is to rank them from 1 to N. I'm leaning toward this because it's hard to balance out letter grades: one can vote all A's to stuff the ballot box, for example.

If I go with 1..N ranking, then the issue of how to sum the weights comes up. I'm leaning toward "reverse squares". For example, if N is 5, then #1 will get 5x5 (25) points, number #2 gets 16, etc. 

A linear weight doesn't feel right. However, if I make it complicated, then voters' eyebrows will dance about their face, undermining confidence in the votes.

For now, this puts aside issues of factoring in effort involved for implementation.
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CategoryDecisionMaking