out for more space in your fridge... in if you dont want to drill in side of fridge ( be careful there could be coolant lines in the side of the fridge )
In the fridge the first night your CO2 is in there you will notice a significant drop in pressure, this is fine and normal. If you warm the keg back up it will rise again
Inside the freezer = one less keg. Outsize the freezer = unsightly CO2 tank sitting next to your freezer (not everyone cares about this, but mine is in my living room, so I opted with option 1).