Tanuki I'd assume is the most populated server. But even if its the most populated server; its definitely dying, which is very sad (meaning hard to find leecher's/rm)
I stopped playing because all my friends moved on as well; so I can't say much of the current economy. The economy before was fairly inflated. Still, I had a blast playing it, so if you haven't played it, and can find some people to hang out with, it would be definitely worth your time.