I think the best "hub" airport I've transited through has to be DTW with NW. They've got a huge terminal, but have quick tram service from end to end and who doesn't love the trippy "mood tunnel" between mainline and express? The terminal may get too big at times, but the non-stop service is amazing. You get multiple option to Asia and Europe from the same airport, very few North American airports give you that flexibility.

Out of US's hub airports I'd say PIT is my favorite to connect through. Though flight options through it are diminishing, I always run into considerate employees and the low traffic combined with huge capacity makes landing-to-gate and gate-to-takeoff times minuscule. I once had a five minute connection to the last flight out (late departure) and they held the plane for me and for my bags.