I have never used a vertex, so I can't comment there..except for the fact that I hav enever heard anything bad about them. the only recommendation I would make is to look into one (whichever brand) that offers two speeds. My proshop has an old jayhawk with one speed ---> slow. It is painful to try and polish a ball on slow speed. At home I have a Donkee (yes, they may not be the best of spinners, but at the time I bought it, the price was very good and it did offer 2 speeds). This model offers two speeds, a slower for sanding and a high for polishing. It is much easier to obtain nice results polishing a ball at high speed, although certain balls tend to be fairly unstable when rotating at high speeds.. thus they vibrate quite a bit. regardless, the little extra $$ spent on a model with two speeds is well worth it (in my opinion).
S^2
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One advantage of bowling over golf is that you never lose a bowling ball
Don Carter