i too have the '38 nazi marked mauser. i also have a no4 mk1, and a no1 mk3. when you're talking combat rifle, you're suggesting ease of use, firepower, accuracy, reliability, etc; not just design. while i think the mauser design is superior to the enfield, the enfield no4 mk1 makes a better combat rifle. the no4 has peep sights, a 10 shot clip for rapid shots, glass smooth action, and additional long range sights. the 8mm is a little more punishing to shoot than the .303. but i also think the 1903A3 is far better than the mauser, but the enfield is a better combat rifle.
apparently the US thought the mauser design was great because the '03 is a copy, but it didn't take them long to figure out it was dated, and thus enter the garand.