The 550 is a bit unique. Only reason the Hitlerwagen has claimed top spot in power is because Nissan aren't shipping 550s now.
550s are hard to come by. Their nearest equivalent, sadly, is the Hitlerwagen. Ford/Mazda are close (and quite good with torque in the lower revs range) but they have the oil pump problem (which is funny as all hell, and a perfect reason to never, ever own one).
Isuzu in their wisdom tripled the chance of a fuel system failure by using 3 fuel pumps - a push pump in the tank, a lift pump and an injector pump. I'm sure the loudest sound at an Isuzu dealership isn't the spanners on the floor, but the ka-ching at the cash register.
For some reason the Colorado is just not in the race any more. Low rpm torque performance compared to the Ranga/BT50 just means it doesn't come close. Raw power from the Navara and Hitlerwagen is just hard to beat.
So what's similar? How about another 550?