Given the above comments, I'll recommend you start looking at the smaller Kubota's and New Hollands. The BX1850 (or 1550 if you can find one), along with the NH TZ18 may be perfect for you. They will both handle the tasks you described, are small and light, and have HST (easier on the knees). The larger of these models (20-24HP), along with JD's 2305, would probably be perfect but come with a higher starting price.