The Japanese have a tier list available which ostensibly ranks each of the VRs:
http://ot.virtual-on.com/index.php?%A5%C0%A5%A4%A5%A2%A5%B0%A5%E9%A5%E0 (the first table)
The rankings are a bit subjective though. Essentially they're compiled by asking the best Japanese players "If Player 1 using VR1 fights Player 2 using VR2, and they are both equally skilled, how many times out of 10 should Player 1 win?" Then they take the numbers and stick them in the table as VR1 vs. VR2. A VR's place on the list is determined by its chances of winning averaged over each matchup.
For example, you can see in the chart that if a Specineff and a Raiden of equal skill play 10 matches, Specineff is expected to win 6 of them. You can also see in the chart that Raiden is actually ranked higher than Specineff if you don't include Ajim (a special character) and 10/80 (a handicapped character) in the calculations.
Buuut, there are some problems with this.
(1) As stated, it's subjective. It's happened before that a really really good guy uses a VR, and ends up skewing the rankings just because of how much he dominates with that VR.
(2) These rankings are determined by polling the best of the best, so they don't really matter for people of normal or even good skill. When you start getting into the really-good range, then your game gets closer to that theoretical limit. And if there's still a matchup discrepancy there, then you know it's a problem inherent to your VR because you can't play your VR much better than you currently are. But at lower levels you still have room for improvement, and that improvement will put you above any similarly-skilled opponent.
Sorry if that doesn't make any sense. I could make some graphs to better illustrate the point.