A good way to understand this is to go on cymbalsonly.com and listen to the soundfiles of say a Zildjian K ride around 2200g and then one around 2000g. Same model, same hammering (now that everything is computerized) but different weights. The major factors in weight is sensitivity, sustain, and brightness (but not necessarily pitch-which has more to do with the profile) However, there are exceptions which are specially made, for example heavy, dark, dry rides and thin, bright, splashes. The best cymbals in my opinion are ones around the thin side of medium (or the heavy side of thin) where you get a nice versatile sound--pingy,washy,crashable,rideable all in one. Then you can choose something flatter (Zildjian K, Sabian HH) or something with a higher profile (Zildjian A, Sabian AA) for different tones once you have the sound picked out. Then come the textures--more hammering (trashier sound [think HHX Legacy, Constantinople]) unfinished (Sabian Raw, Bosphorus Turks, etc)