Hi PR, The 9mm is often considered better for home defense due to its higher magazine capacity, lower recoil, and ease of handling, making it suitable for rapid shooting. However, the .45 ACP offers greater stopping power, which some may prefer for self-defense situations.
There is no right or incorrect answer, it is really a personal decision.
Stay safe & have a great day!

Well first, do you own both a pistol chambered in 9mm & .45ACP? Secondly, both have great defensive rounds available.
For 9mm one could go with budsgunshop.com/product_info.php/products_id/113662/speer+gold+dot+g2+9mm+ammo+147gr+20+round+box />
For .45ACP,
budsgunshop.com/product_info.php/products_id/108170/speer+gold+dot+personal+protection+hollow+point+45+acp+ammo+20+round+box