Upright Freezer
Pros: no height issues, no need to make collar, smaller footprint
Cons: not as much room inside, be careful you get an upright you can remove the shelves from (it's very common to have the coils run through the shelves), it's slightly more difficult/dangerous to drill the door for the taps (vs a collar), the taps on the door are less stable because the door swings
Chest Freezer
Pros: lots of space inside, if you're handy you can turn it into a nice piece of furniture, the collar is easy to drill for taps, the collar is a very stable place to mount taps
Cons: Height (need to make a collar, including wood and insulation), it can be difficult to get a good seal with the collar (which leads to condensation & mold), larger footprint
Both usually require some sort of fan for optimal performance.