I'd say the Sherman got its rep because it wasn't what people now days often compaired it to, the Tiger, the Panther. When what it was roughly equal to and more than capable of engaging was the most common German tank, the Panzer IV. The Sherman was a good tank, it was workhorse reliable, and fairly easy to maintain (superior to British vehicles like the Cromwell in this regard.) And with its 75 or 76mm gun it was versatile.
But it wasn't a Panther, and it wasn't a Tiger or god forbid, a Tiger II. Those machines were far superior weapons platforms, but they were also harder to produce, maintian and keep supplied (All three were gas guzzlers and were not fun to maintain). And the Sherman COULD and did engage Panthers and Tigers with success and not the 5 Shermans to 1 tiger nonsense.
Yes some Tigers had amazing successes, Whittman for example in Normandy. But you know what killed him? A Sherman.
Was it an amazing tank? Nah, was it a good tank, yes.
Whilst the Sherman was also a victim of some poor decisions (the delay to adopting the 76mm gun for example), a change to a different machine would have imposed too many delays. The US was mass producing Shermans and either doing a significant overhaul to the design or even halting it to produce something bigger would have affected that production rate as well as causing issues with training and supplying them as you'd have to make parts etc for the new vehicles.
Basically the Sherman was okay, it wasn't amazing, but it did its job well enough and when it did run into Tigers or Panthers, it still didn't do too badly outside of a few very specific instances.