the king tiger would be the best tank apart from serious problems to do wtih parts and replacements. by the time it was in production  germany was on its knees in an industrial sense and had real problems keeping its forces in supply. the king tiger did need high maintenace and if it had been in use early war it would've proved it's use and class. as it was, allied control of the skies ensured these monsters staqyed where they were w/o repairs [not forgetting fuel supply problems].
it has often been called underpowered. not so... the engine was more than adequate. but, as i said, it required high maintenance etc.
the T34 has to be the best. easy to manufacture, wide tracks to cover most terrain types, relatively light weight, sloped armour [think about it.. a 60mm armur at 90 degrees is still 60mm... at 45degrees this 60mm becomes doubled if not more armour with the added ability of deflecting AP rounds!], excellent suspension. even in '41-42 they utterly outclassed the german PzIII and IVs which still used poor performace AP guns [T-34 had the 76.2mm gun, more effective than either the gerry 75mm L24 of the PzIV or the 37mm/50mm of the PzIII].
ok, they had a 4 man crew and lacked radio equipment [so, the commmand control of the germans gave them a tactical edge] but this could've easily been resolved.