Seems to me that both should work quite well.. but that might depend on the severity of the sludge. If it's bad enough I would be concerned about either cleaning "too well" and putting too much into circulation.
In my mind, this also depends on the car/engine you have in mind. If the car calls for lighter-weight oil, then I don't know if HDEO is necessarily your best choice, because those are all heavier-weight oils, which would mean that PUP would be the best choice.
All other things being equal, I'd probably just go with a decent SM/SN-rated HDEO and save money.