Im on a "fill in the gap" kick and have been for a few months. The Cromwell, while a great 'lil tank and one the Brits can be proud of, it is too close to the M4A3 (75mm) in performance save for the speed to add it at this time, imo. I'd love to see it added once a few other GV's are put into gameplay.
M18; multiple variants of the M3; multiple variants of the SdKfz 251; StG IV, Marder III, Hetzer, etc.