Neat graph today over at MMO-Champion showing the ratio of different classes at different levels of valor points. Basically what classes are raiding and how often compared to others.
What is interesting is that you can infer which classes people generally use as alts and which classes people generally use as their "mains". Druids, paladins, priests and warriors all trend upwards and have a larger representation at higher valor point levels. Death knights, hunters, mages and rogues all trend downwards although mages stay more constant.
Warlocks and shaman are oddballs in that their representation fluctuates rather than trending up or down. I found shaman particularly interesting because they peak in the mid range of valor points. That is interesting because my shaman is my second raiding toon, but I don't put as much effort in valor point wise as I do on my main. The shaman representation peaking in the mid range indicates to me than many other use their shaman as a secondary raiding toon that they don't play as much as their mains.
My theory on warlocks that peak at 25k valor is that they are also secondary raiding toons for people, but there are also more warlock alts hanging around.
The only other interesting data points I gleaned were that hunters drop off fast, like falling off a cliff fast, and that mages fall off, but not very much at all. My take on this is that hunters are the most popular alt class and mages are appealing to casuals. I earned some warlock points there calling mages casuals. I didn't exactly say that, but what I am getting at is that mages appeal to people playing alts, playing casually as mains, secondary raiding toons and hardcore raiding mains almost equally as much. Not sure what that means, but it is interesting.
What we can take away from all this is that if you are starting a new toon, pick one of the big four: druid, paladin, priest and/or warrior.