Depends on where you sail. If I was doing an ocean passage I'd want a full keel, a fin in heavy seas is much more apt to be squirrelly. If you are not on open seas a fin is much more maneuverable. I had a Cal 9.2 that turned on a dime. But in big following seas one must be really be diligent at the helm. It's a great deal of work. The above 3/4 keel and skeg hung rudders are a good compromise. I plan on blue water cruising, Bermuda...ocean crossings. My choice for that is full...
Daledog, Many of us here in N. America thought the same as you and most still do about the full keel/fin keel in heavy seas etc. But like outbound said those ideas are outdated. The new designed boats being built over in Europe have solved those problems for open ocean crossing. And we here in N. America still remain clueless that for the last 10 years on the other side of the pond they have been enjoying wonderfully built boats that behave better in many ways than our traditional boats on all points of sail in big water as well as small water.
Boy if you have not read the "interesting boat" post take a look at it there is lot of good stuff in it.