I've been been looking for a good scale sized post war style K4 and finally bit the bullet on a 3rd rail "High Iron" version. It amazes me how there hasn't been what I'd call a "definitive version" yet, and that the ones that have been made are quite difficult to find. The K4 sure did not get the hudson treatment!
In my opinion, the High Iron is the best looking but it probably has the most mechanical issues of the bunch. The later MTH releases look very nice but the drivers are definitely too small and the Ps3 version barely if ever comes up for sale while the original 90s ones are a dime a dozen. The ex K-line Lionel one seems to be on point proportionally but I just cannot stand the giant smokebox door hinges (MTH fixed this issue on their PS3 release) as well as the finish on the wheels and siderods, although I'm willing to bet it's the best of the bunch operationally.
I'd love to hear which everyone prefers and why. Here's hoping I didn't make a mistake!