Mmmm ... the Sherman seriously sucked in a one-on-one duel with a Tiger or Panther, but so did the T34. Of course Firefly Shermans (equipped with the Brit 17 pounder (85mm) gun) could easily kill Panthers and give a Tiger a seriously bad day if they caught it from the side or rear ... but for some reason the US rested this mod. (Canadian Fireflys took out Panzer Ace Michael Wittman's Tiger ... and the rest of his Tiger platoon ... a few days after his single Tiger had effectively wasted a whole Brit armoured division.)
That said the Sherman's big strengths were that it could take out pretty well any other German tank ... including the Mark IV, that its numbers were massive, that its chassis formed the basis of many other US artillery and armoured vehicles, the it was easy to maintain, relatively speedy and adaptable to add features ... like the fork on the front that made the Bocage campaign so much easier for the Allies.
Despite its limitations the Sherman was a war winner.
That said, it was not until 1948-49 that the US has a battle tank worth the name.