T-28 served to the end of Second World War, and I understand it was better than some of the single turret light tanks with 37 mm gun or smaller.
i'm not sure the finnish ones should count. (by the 40's most active T-28's were in finnish hands, not russian.)
and i'd question the 'better' claim.. the T-26 might have been poorly armored, but the T-28 had terrible suspension, Engine and Transmission that were a never ending source of problems even when well maintained, and unlike most of its contemporaries, it didn't have much room for upgrades and improvements. (would have had to redesign the whole tank)
it also was overcramped inside, and the hatch layout was borderline suicidal, especially if you were in one of the secondary turrets.