Longevity is important but peak is too, and adding up AV gives too much credit for longevity. For example, this year Darren Sproles passed Terrell Davis in AV. Some options that are better:
Number of Pro Bowls + number of first-team All Pros with that team.
Total AV over his best 6 seasons with that team.
Some kind of weighted AV (such as 100% of his highest season AV with that team + 99% of his second highest AV + 96% of his third highest AV + 91% of fourth + 84% of fifth + 75% of sixth + 64% of seventh + 51% of eighth + 36% of ninth + 19% of tenth)
HOF Monitor score, limited to seasons with that team.