The Susquehannock is an awesome trail. I plan on hiking it in its entirety this summer. I do much of my hiking in McKean, Potter and Tioga counties in northern PA. It is truly a beautiful place where I rarely see people. I especially love the West Rim Trail in Tioga County. I am not sure if it is my favorite, but if you are ever back in PA it is certainly worth the trip. It winds through the "Grand Canyon of PA," and the views are fantastic. While the trail is only thirty miles, it is close to others so there is a lot of different options in the area. PA is often not mentioned among the great hiking states, but is truly fantastic. The North Country ,Quehanna, Black Forest, Donut Hole, Mid-State, and Loyalsock trails are also great choices.
Another fantastic trail is the Grafton Notch Loop Trail in western Maine. Technically only half of it is open because of a dispute with a land owner, but I hiked it all last summer. There are some very nice climbs over a variety of Maine peaks. Moose are in the area, and I had the chance to see a large male. In addition it is close to the Presidentials of New Hampshire which provide countless other opportunities. Excellent locales for putting in some beautiful miles.
While I really don't have a "favorite" trail, these are some special ones.