Smart, loyal? German Shepard hands down. Protection and deterrant factor are way off the scale as well. Downside here is you mention going to college. Any large dog will need lots of room and a lot of places will not accept dogs over 15 lbs. You will limit your living choices as a result of the dog you own. Think carefully about this before you adopt any dog.
As a shepard owner, I can tell you they shed constantly and like to keep their stink factor up there. Take them for a walk and they will insist on rolling on every dropping and dead animal they can find. The high intelligence also demands dedicated attention on your part.
I'm with you on the small dog issue. They tend to be yappy and bad tempered. Still, I have friends with Shi Tzu's and they do provide good companionship, but as protection, it's pretty hard to take them seriously.