M4 Shermans have gotten far less respect than they deserved. At the time they first hit the battlefield, El Alamein(?), they were much better than what Rommel had. Even later in the war, in Europe, they were still very good GP tanks, as most of their engagements were with infantry and fortified positions (i.e. their very good 75 mm HE shells).
But, yeah, used as designed, current Rev M1 Abrams is currently one of or the best MBT in the world. Its 4 decades of service also demonstrate that the original design allowed for significant upgrade capacity*.
* A contrast with contemporary Russian MBTs which, while upgraded, have in approximately the same time gone from the T-80 to the T-90 to, supposedly, the T-14 Armata. The T-14 has not shown up in Ukraine, despite the very substantial degradation of Russia's tank force, so it may be somewhere between unanticipated heavy-duty debugging and vaporware prototypeville.
