If that's the question, then I conclude that the Swedish Strv m/41 was the best tank of the war. Stronk Czech (rivetted) tank design, and located many kilometers away from the fighting! Sure, 160 mm or whatever the KT has for front armour sounds strong, but take just one kilometer, and you're already at 1 000 000 mm! Really, at that point, KT or BT-7, it hardly matters in comparison. Not being at war also heavily increases survivability.
Maybe only tanks of nations at war counts? Then I would say the Norwegian L-120 tank. I know people say that the USSR focused on Quantity over Quality, and T-34 stronk blahblah but the L-120 can be considered nothing short of a complete revolution in operational and strategic thinking. Focusing on minimum possible quantity (1 unit) and minimum possible quality (a Swedish experimental tank with its armor replaced with iron plates for economic reasons, armed with one machine gun), but maximum possible crew survivability (the tank was considered so useless that it was left at the equipment depot when the regiment mobilized, thus it was never crewed in wartime, thus 100% wartime crew survivability).
But seriously though... armored recovery vehicles, that's something I would like. You still serve in the army, but behind the safety of your own lines. You are also going to spend your days fixing the awesome armoured legends of your nations, but not, you know, operating them and killing people while dying. I think I would really like that. I'm a peaceful sort of person.
I might not have taken your question seriously, but this is my honest conclusion.