I have both, but dispense from my fridge and ferment in my freezer.
Fridge-
Pros:
-I can still fit four corny kegs in my fridge and run the taps out the door. No additional work in building a tap tower or collar.
-Usually easier to find exactly what you want used on craigslist for less money (at least in my case)
-I still have a freezer to use up top for keeping my mugs frosty (though I tend to use room temp mugs these days, and the freezer is full of frozen baby food... lol)
Cons:
-If you mount the taps through the door, you have to be careful using long tap handles or you'll open the taps along with the freezer door.
Chest Freezer-
Pros:
-You can fit a crapload of corny kegs in there, depending on the size freezer you get.
-Easier to be customized into a bartop setup, if that's what you're looking for.
-Can be used for fermenting and serving, if you space your brews out enough.
Cons:
-Moisture builds up inside... a lot. Products such as damp-rid help, but don't fully eliminate.
-Usually harder to find if you're looking for a cheap used one. YMMV
-You need spend additional money on a temp controller to keep it at serving temps. Which you can either build yourself (search ebay temp controller on here) or buy a pre-built one such as a Johnson.