1 Ton Dual or Single Wheel?
If your running a Dual One Ton you can manage the bigger stuff, but unless your truck is built Rock Solid a 12" chipper is a lot for a One Ton, Day in Day out, it can be hard on the truck especially full loaded. Best Chipper is the one you can afford bottom line but I would have an old, trustworthy and seasoned treeman with you when you go to look at stuff. He has nothing invested in the machine and will help you keep your head cool and also not let you pass up a good deal. I recently helped a friend get back up and running with a truck a chipper and he was under a lot of pressure and I had to help him along through the process.
He got a 1 Ton Dually Dodge Cummings and he just picked up a Bandit 150, nice set up and the chipper was in good shape for its age. To be honest, most of what vermeer is selling... Its junk, it's poorly designed, under-built and a nightmare to fix. Bandit or Morbark are Great Units, I've owned 3 morbark chippers and can tell you they are built like tanks, made for the abuse we put can them through... Bandit's are built lighter but they do not comprise quality.
You have to look at how many removals you do to figure the size of machine you need. You may also think about how often your able to access trees from the front and weather your taking or leaving wood most of the time. That's all critical in how much chipper your going to need, but whatever you buy MAKE SURE ITS DIESEL. That is an absolute, any gas chipper will be slow and ineffective and possibly very problematic down the road, if it's infeed is too large for the motor the motor will go. You may hear a few other opinions, ignore them, just look at the rpm / torque curve chart for gas and diesel engines and you'll begin to understand.
Also, a 65xp with a diesel is a great startup chipper, just try to avoid the Duetz Diesel, it's not a good engine long term, Hatz or Lombardi is much better for that sized unit, small CAT's are also junk, stay far far away from them. I know a lot of guys who have built themselves from the ground up with a 65xp, just make sure its diesel, and your core business is not doing removals most the time, other wise bigger is better and then get a bigger chipper. Look up what you can tow and what your local bylaws are for trucks and wieght ratings and that too.