You have to go by price, condition, and of course brand loyalty. If you do alot of trail riding the Z is supposed to have the best bottom end. Ofcourse the 200x is a 4stroke and therefore more likely to be reliable and a long lasting ride. The 250R is a little old for my tastes, parts are liable to be very hard to find and expensive when found. Now most of my opinion is formed by reading others posts and I am sure that there are more reasons to love/hate either but I would go with the Z personally, but you will want to look at what you are getting and the price you are paying for it. How much is being asked for the Z, and can you post pics?
Barry
There are no stupid questions, but there are alot of stupid people out there that ask questions.
None of us are capable of screwing things up as bad as a group of us.
"NON SIBI, SED OMNIBUS"