I guess it really comes down to what you fear most and what you enjoy most.
From a fear perspective M1s are drying up. They aren't being made. Supply is decreasing. There is a strong argument the M1 will be the hardest to come by in the future.
Another fear would be a new AWB which would put the AR and the FAL as top choices. Not sure how much I really fear this option, but it is a thought to weigh.
Then would be a handgun ban making the 70 series 1911 a top choice.
From an enjoyment perspective...
The M1 has a ton of US history, shoots a heck of a round, and is fairly accurate. Yeah its a bit heavy and only holds 8 rounds, but boy does it put a grin on your face when you shoot it.
The FAL is right there in terms of shooting a heck of a round and has better ergonomics, though not near the personal history for us in the US.
The 1911, well, what can I say that hasn't been said about it a million times. Its a great pistol, with great history, and is a blast to shoot as well.
The AR is probably the most useful rifle of the group, at least in my area. I see it as a great tool. Fun to shoot but not as fun as the others, though it does its specific job excessively well which is worth a lot. You can get any flavor you like with as many or as few bells and whistles as your heart desires.
So what do you like? I went 1911, AR, M1, and have yet to find an FAL, though I would enjoy having one. I see all 4 as vastly different and honestly something that you have to determine what you enjoy the most. At the range, the M1 is the most fun. Every time I hear that ping I grin. Every time I pull the trigger, I grin. Its something that I enjoy beyond simply sending lead down range. For that the M1 is my vote of the group. I do like my 1911 but I am much more a rifle guy than a pistol guy. I like the AR, it does a lot well and is good at what its designed for. It doesn't give me near the grin of the M1, but it has far more function for me as well. In the end though, you may enjoy certain aspects of shooting/firearms and find one of the 4 specifically more enjoyable to you. And thats what matters. Buy what you want. Buy what you enjoy.
Zack, You probably saw and M1a, which is the son of the Garand. It is still made today but there are many differences between the two systems.