I happen to own both, and like both for their own qualities. Cruising-wise, the full keel offers more volume lower down in terms of stowage and tankage generally than the fin keeler, and frequently either has a skeg-hung rudder, or the rudder is supported at the end of the keel itself, an inherently stronger installation for steering (two points of support instead of one, and less chance of damage from impacts/grounding).
Full-keelers are invariably slower for the most part, but frequently have a higher "comfort" rating in heavy seas than fin keelers, and are less sensitive to weight in the ends, another consideration for the distance cruiser.
Perhaps a "compromise" design is the semi-full keel boat, sometimes known as "the cutaway forefoot" and commonly seen with "the Brewer bite", the space between the keel end and the skeg, as seen in many of the designs of Ted Brewer.
Really, it comes down to the type of sailing you intend to do...I like light-air, go-fast fin keelers, but I chose a full keeler for reasons beyond speed, and because I feel in the end, a full keeler has advantages apart from pure sailing qualities (although I have not been particularly disappointed in those). When recently in six-seven foot seas, which is biggish for Lake Ontario, I noticed the motion of the full keeler was far smoother than similar waves in my fin keeler, and while less "exciting", was also less exhausting...I could safely move about the boat without fear of sudden slamming.
To each, however, their own.