Planning to visit Mount Abu.

We are planning a visit to Mount Abu. From there we have time for 1 more place. Which one will be better Jaipur, Udaipur or Ajmer? We're thinking Udaipur as it's closer. Are 3 days for Abu n Udaipur each enough? Also can somebody suggest if Chittorgarh or Kumbhalgarh fort is possible from Udaipur. If yes, which one will be better?