There is only one badge for each award, so being able to vote for 1st, 2nd and 3rd would make it more complicated – and would cause no end of arguments about how the final winner was decided – there are so many different methods for allocating preference votes to come up with a single winner that it would be a major headache for those of us behind the scenes. Sorry @benbob , but you'll just have to make a decision!
A mixture of quality and quantity is what we're looking for, someone who posts consistently good messages regularly. Another way to think about it is ... who would you miss most from the forum if they weren't there?That generically means the person you felt has made the best "overall contribution" rather than a specific thread. Albeit you might have a member that makes fewer posts you prefer that are all of exceptional quality. In eithercase it doesn't mean one specific thread.
You just have to weigh-it-up best you can though obviously you are going to be looking for quality posts nonetheless.