I prefer the slider. You need to do a couple of things. Then ask yourself what you want to build and what saw will best suit your needs. We have both saws in our shop. I would hate to give up either one of them.
Different jobs call for different setups.
We do frameless cabinets and find the vertical saw faster, safer and more accurate for panel sizing. This is what it is designed to do, and it does it well. It is a specialized saw and not as versatile as the slider. Which would be better would depend on your personal preferences and the type of work you expect to be doing. The last post hit the nail on the head.