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I don't have personal experience with any of your three potential candidates, but I have looked at their specs and, having bought many canoes without personally trying them out, I can give some educated evaluations of the three against your desired performance criteria.
I believe the only Sportspal with a square stern is the 13' model, which can carry only 555 pounds. This would be a wide canoe to portage and the least likely of the three to have a comfortable capacity for two adults. Sportspals are also not of the construction quality of an Esquif.
As between the Esquif Cargo and Heron, which are both square sterns that can take a 3 hp outboard motor, the Cargo is MUCH bigger, longer and heavier. I really doubt anyone would want to portage 95 pounds even if they are young and strong. The Heron, at 69 pounds, is reasonably portageable, should be able to carry two adults with its 800 pound capacity and, at 38.5" beam, should be stand-up-able for one person, but I'm not sure about two at the same time.
Just based on specs, I'd say the Equif Heron would best meet all your listed objectives as a portageable canoe for both tandem and solo use. Price can often be the determining factor in making compromises, but that is a separate issue known only to you.