Dahon Speed P8 and new Brompton for me (both weigh the same). For short distance carry, P8 by the frame as the seat is too off center of gravity. Brompton can be either seat or frame, but frame is a bit better from a CoG perspective.
For longer distance carry (eg, across a beach, or lots of stairs) I think I'm going carry the Brompton flipped upside down, frame tube resting on my shoulder. Just like airplane carry-on luggage, I find 25+ lbs bricks awfully awkward to lug along at your side for any distance - you have lean the other way to compensate, walk with a bit of limp, and still can't make it though narrow hallways. However, resting on one shoulder (using an arm and my head to secure/balance), the CoG is more in line with my own, walking is normal, and I can make it through narrow hallways (although you now have to watch ceiling height if you are tall).