get the .45 first, since that's what the 1911 was first designed around. Eventually you will own several of each!

the .38 super is a classic, but due to economies of scale the ammo is twice as expensive as the very similar 9mm, (but my LGS had some in stock last time I stopped by, unlike 9)

After reading Bill Wilson's book "Gun Guy" and binge watching Wilson Combat videos (they like 9mm), and CMP allowing 9mm for IEC matches, I'm slowly and reluctantly warming up to the (shudder) thought (gulp) of a 1911 in 9mm (uggghhhh I said it....) (actually I didn't say it, I typed it)

a lightweight commander in 9mm maybe for carry, NM gold cup for Bullseye/EIC/LEG matches in 9mm.... maybe... I'm not there yet....

Poole