The 1911 is a favorite of mine, but NOT in 10MM. I have owned both pistols. There was nothing to choose between them as to accuracy.For some reason, my G20 was not real reliable, but I suspect most G20s are very reliable. My Delta in stock form was 100% reliable. While I didn't break anything in the Delta after moderate use, I really felt like the Delta was a bit overmatched by it's 10MM ammunition. One fellow 10MM shooter told me that his Delta cracked the slide through the locking lug area, ahead of the ejection port. He said that Colt replaced his Delta under warranty and that he sold the replacement gun without shooting it. While I am perhaps not Glock's greatest fan, the G20, with it's heavier slide construction and much greater slide mass, would be my choice, between the two, for durability using the real 10MM ammunition...ymmv
Ps, If shooting some of the later factory 10MM ammo, or reloads, loaded to ballistics similar to .40 S&W, I think the Delta would last virtually forever. Using the "real" 10MM ammo,e.g.,the old Norma, or similar, 200 @ 1200, CorBon 165 @ 1325, 135 @1475, Buffalo Bore 180 @ 1380 fps, etc.,I'd be more confident in the G20's durability. My personal favorites though, accurate, reliable, durable,etc, are the S&W 10MMs...