I used to have stronger opinions about guns and would argue them on gun boards...
Then I found myself in a combat zone for the first time issued 2 weapons I wouldn't have picked and had to trust my life to them. I didn't even get to test fire or zero them before going "outside the wire." The weapons were an AK-47 and Sig P226. The place was Baghdad circa 2005 and I was a contractor. I figured I was being paid to take the higher risks so I did.
Anyway, I really learned the AK and analyzed its strengths and weaknesses, overcame the crappy ergos with training and practice, overcame the crappy sights by mounting a RDS on an Ultimak rail.
As for the Sig, I thought I hated DA/SA guns, 2 different trigger pulls and all that. Well, my mentors taught me to shoot it well and I fired and dry-fired the snot out of it! When I got home I bought one and it is my main carry gun to this day. I can run it as fast and accurate as anything including hanging with the best shooters at the classes I've attended, even if they're running 1911s.
Now, I only have mild firearm preferences and no strong opinions. I look at them as tools and analyze any given weapon's strong point and weak points, looking to maximize the former and minimize the latter through training and hardware.
As for the M1 carbine, I have a GI M1 and love it! For HD, set up with an Ultimak rail, micro RDS and light (and good 110g SP ammo), in practical terms it wouldn't give up much to an AR in a typical HD scenario.
That said, I can't fathom how any truly objective analysis of an M1 vs. an AR would put the M1 on top
Name the category; size, capacity, ergos, cost, terminal performance, ease of modification, penetration in walls and even weight, the AR can beat it. That is why an AR-15 SBR with RDS, light and sling is locked under my bed and not the M1 carbine. I'd happily bet my life on the M1 carbine...but I have something just a little bit better all-around (a lot better if the M1 is in stock configuration).
The M1 is a great handling little rifle though, and set up right, absolutely an outstanding HD arm. I don't need to build up any straw-men to tear down so I can argue 1 vs. the other.