Wow, no one posted this before on any gun forum! I hear some computer genius invented a search function.
Anyway, I am a great believer in the empirical test rather than internet opinions without such. So - take some quality 'tactical' shotgun classes, take some 'tactical' carbine classes with common carbines as used nowadays - the ARs, the AKs, the Mini-14s, the other 223s or 300s (whatever), the PCCs.
Then run them in competitions. Three gun, specific defensive USPSA (PCC), IDPA or club matches that do the 223s.
Then you have a basis of truly deciding. Otherwise, stopping power, capacity, recoil, short stroking, easier malfunction clearance, easier to manipulate as you clear the house (OH NO!), you don't to aim (OH, that's news - try a competition), will it hurt me in court, etc. etc. Guess how many pages we can go.
Can we do 1911 vs 9mm or SA vs SA/DA vs DAO vs Striker? Or I carry a BP revolver for SD, what's wrong with DAT? Red or White wine while reloading?
How about that Glock grip angle - I just can't shoot it!!!