I'll say an AR due to the ease of changing calibers. I could have multiple uppers in different calibers and just swamp em out.
cheater
I went M1A... I have never had a FAL and I am starting to feel like I have been missing out. I like the .308 round.
If you're going to go through the trouble of feeding it, and having a gun that isn't man-portable, and hard to shoot, and jams, and requires electricity to operate, at least make sure it's a Dillon one...GE Minigun