The best Colt is the Python. I had gotten away from 357's for awhile and recently purchased a Trooper Mark III (6" blue) 357. I frankly can tell little difference between the Mark III and the Python for fit, finish, trigger, and accuracy. These also tend to be one of the less expensive Colt 357's. I recommend it hightly. The only reported weakness of the Mark III is that you should resist dry firing it due to possible firing pin damage.
The Trooper Mark III was revised into the Trooper Mark V. Have not shot one of these, but the main purpose was to allow quicker double action fire. The King Cobra, Lawman, Metropolatin, etc are all variations of the Mark V action. Have not shot any of these, but I would assume they are consistant with Colt's standards.
The Trooper 357 or the 357 Magnum models were introduced just prior to the Python being introduced. It is said that the hand fitting and overall performance of these guns are consistant with the Python. They are good ones to acquire. I have the 22 variations, but not the 357's or 38spls.