I went through the decision on this a couple of years ago. From my research 4 post lifts were great for stacking / storing cars along with working on them except for suspension / wheel / brake service which would require individual jacks optioned onto the lift. 2 post lifts are the best for servicing / working on your car but not a great choice for storing / stacking due to suspension sag, some debate that though. Either way you will want to lay out the lift and columns in your garage as a mock-up (I used corrugated sheets and large tubes as the columns) to see how much room it actually takes up, it's more than you would think.
Unfortunately a 2 or 4 post lift was not an option for me due to limited ceiling height and bumping it up would not work either. I ended up going with an Atlas scissor lift that I recessed into the floor, bought it from Greg Smith also, been very happy thus far. Link to the Project:
Group Purchase on Atlas Scissor Lift - Rennlist Discussion Forums
Knowing what I know now for my particular situation I would of done this instead:
In-floor Scissor Lift Install - The Garage Journal Board