If you're using HVAP against a target where AOE is more useful than penetration, you've made a mistake, and the HVAP round has much better penetration and a faster ROF than the M4A3E8's main gun.
Taking an extra hit with the extra 80hp is nice, but the Easy 8 is also slower and more expensive than the 76mm Sherman.
Reload time for for HVAP is 6.1 vs 6-6.6 average 6.3 the difference is minimal.
Penetration fer is around 6% better so I wouldn't call "much" better but that is just me.
One has to switch munition the other does not...(on another note for quite some time some people claimed that Sherman was inferior because it could use HE rounds

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Not only it has more HP but more armor. A Easy8 has allot better chance vs PzIV than the 76mm.
Both units are fine and both units are more cost efficient than PzIV J