Not all 75s are the same:
The M1897/M3 gun are pretty similar in performance (not very much gun for anti-tank work, but fairly good as an HE thrower)...
The M2 gun is slightly lower velocity, but still 'medium velocity' ~ this was the early gun for M3 medium hull mounts, before the longer M3 was adopted.
Going upscale a bit, the 76.2mm M1 gun is comparable to the KwK40 L48, in terms of velocity and armour penetration, and significantly worse as an HE weapon than the M2/M3 75mm.
The Panther's gun, the KwK42 is much harder hitting in anti-armour capability than the KwK40...
Going downwards there are the German KwK37 L24, the US M2 Howitzer (the weapon on the M8 HMC), and the German IG37 and IG18 (plus a few other 75mm types in more limited numbers) in that order of velocity and 'hitting power' ~ these all are 'good' HE throwers though... In order to obtain useful mid-late war anti-armour effect these all relied on HEAT ammunition, with maximum penetration of roughly 75mm (calibre). This is far less than the maximum penetration at short range of the other types, and HEAT tends to have lesser BAD effects for similar degree of overmatch to AP or APHE rounds.