guns are personal preference. i have shot many over the past 11 years of playing. you need to make your own decision on what you want in a gun and go from there. don't get a specific gun because someone else said so. like above mentioned about the ion. i hate when people dog them as mine has served me quite well in many tournaments and still gets regular use when i go play recball.smart parts, proto,eclipse, dye you can't go wrong with any of them. shoot what feels good to you as each of the ones you listed has basically the same features and everything needed to be a capable entry level tournament gun.
buying used is not a bad idea either as you can get more bang for your buck.