I'm just now making the switch from a portable/chest style fridge to a "built-in" fridge. Specifically, the Truckfridge TF49. It's running the same Danfoss 12v compressor that all the other quality chest fridges are running, so the power and "level" requirements are pretty much a push between the two types. The one obvious difference is that people always say that the cold air will "spill" out of a vertical fridge, but that always sounded strange to me since the main thermal mass in the fridge is the *stuff* being cold, not the air. The VW guys have been using this model as a drop-in replacement for the old Dometic 3-way fridges in the westies for many years, and they swear by them, especially since the smaller Danfoss compressor means they actually get
more storage space in the same cabinet volume. Some have gone so far as to rebuild their cabinetry to accommodate the larger TF63 as well. For me, the rated volume of the TF49 is already larger than my outgoing Edgestar FP430, so I'm sticking with that one.
Anyhow, as far as are there reasons to pick one over the other? The driver for me was form factor. The "shape" of the box and how the door opens can sometimes be a better fit for your space.
The chest fridges require overhead clearance to be able to open the doors, making their "consumed" volume larger, unless you can put them in a drawer under something else, but I couldn't manage that in the available space in my van. (I don't have a high enough ceiling to raise the bed enough to put the fridge underneath, for example). Instead, an upright built-in fridge is shallower and narrower, but taller (but not as tall as a chest fridge with the door open), so I'm able to fit it into a cabinet behind the driver's seat. As a bonus, my cabinet, with a slightly smaller "footprint" than the chest fridge, will also fit a 5gallon porta potti underneath the new fridge, along with a decent size drawer for a stove, neither of which really would have fit in the space the chest was using. (I did have a small bin in a cubby underneath the fridge for a while, to be fair, but this is WAY more useful.)
I'm still putting the final poly coat on the cabinet today, but here it is during construction so you can see what I mean:
The upper compartment holds the TF49. The bottom compartment will have a drawer for the stove and hold a Thetford 550p or comparable Dometic 5-gallon porta potty that can slide out. In comparison, the FP430 was deeper (protruded further into the middle of the van) and slightly wider than the cabinet, and I couldn't raise it enough to be able to put the potti underneath it and still open the lid.