Questions are asked for multiple reasons, to find answers, to find understanding, to diverge down untrodden thought paths. Mainly in the BuffyVerse its to give the audience some exposition without an unbroken, long winded lecture.
Both Tara and Willow clock up some questions in their time. But who asks the most? No particular reason for the question, it could be a question about the meaning of life, all the way to asking to please pass the salt.
Who asks the most questions?
Willow - Answers are the follow up to a question and Willow has a brain that provides plenty of answers, but how many questions did she ask to get those answers?
Tara - She might not have all the answers but she certainly seeks them, how many questions does she come across when on search for answers?
No both or other option this week, the fence is being repainted (nothing wrong with fence sitting, great perspectives of both sides). Maybe you'll even go through hush - taunt the colour blind to find the canon answer. Or it will be more of a theoretical, who doesn't like answers answered as questions in a never ending chain. It's not amusing, until it is.
They both ask a lot of questions. Each one has a different area in where they question. Id say they likely question things at the same rate so id look more for how they answer them. I'd say Tara has more philosophical or practical questions (mainly about books) where as Willow has a science area in her questioning and often there's a method to answer those questions that don't always raise more questions so id say in that brief time Tara might get a sneaky little question in there. So by a bees dick, I'd say Tara.