Any difference between the one that folds and the one that does not (that resembles the old kamisori)?
Also, will these razors take a Schick Proline, or do you have to use a Feather-branded blade?
If you're buying new, then go with whichever one you like more since the price difference is likely to be very small in comparison to the peace-of-mind that you get when you get what you want.
If you're buying used, go for whichever is cheaper as they both pretty much shave the same. The kamisori is every bit as good as the folding style and objectively I think it might be better. To me it feels a bit heftier in the hand, the gummy grip is very secure even with wet, and allows you to adjust the angle by simply rolling the 'cylindricalish' handle between your fingers.
BUT....
You need to either buy a cover for it (which is ~$10), flip the blade when you store it (cutting edge inside the body of the razor head), or be very careful that someone doesn't accidentally cut themselves. And that to me, is a large draw back. It's also part of what makes a kamisori-type razor what it is though.
It's difficult to choose and if you asked me which I prefer more, I'd just say I'm happy with either. Not much help I know, but just letting you know that IMHO, they're both great.