The bigger the dish the more signal it can gather and the weaker satellite signals it can pull in. So your first consideration in choosing a dish is to make a list of satellites you are interested in receiving.
If you are buying a used mesh satellite dish, be sure it has the smaller diameter perforations or a significant portion of Ku signals will pass through the dish. Do not waste your time buying a fiberglass dish as that is early technology and will be guaranted to have C-band only mesh embedded within. If you have consideration to purchase a solid metal dish, or one piece mesh dish, stand aside from it and sight across it to be sure it is not warped - if so, do not purchase it regardless of the price. In buying a new dish, a solid dish will not necessarily have a greater efficiency rating than a mesh dish; look at the dish specs and see its efficiency rating which is the percent of signal that hits the dish is actually reflected into the feed - the greater the efficiency rating, the more gain the dish will have.
In another consideration of mesh vs.solid dish, at wind velocity of about 50mph the two offer the same resistance to wind forces; a mesh dish is easier for the actuator to 'push' around though on smaller diameter dishes (less than 2.5m) today's actuators handle a solid dish with minimal problems.