Oh, how I love when these threads are started. I don't know if what I have to contribute to this is going to be useful (or mentioned and I missed it) but here were my thoughts based on the *original* question.
If you asked me what to get with your $2000 I'd go for 3 different platforms in their off the rack configurations. The reason I say this is from my own experience when after I blew my whole wad on my first AR-15, I caught the black rifle bug, and couldn't wait to get another. There are different things about each platform that you may or may not like/appreciate, and until you shoot them all you can't know, right? If you really want to cut to the chase, the Gun Bible from author Boston T. Party does a point by point analysis/comparison of all the platforms mentioned here. I can summarize: get an M14 or a FAL for a true battle rifle; get an AR if you can't handle the recoil.
Seriously though; these threads always go all over the place, so if one were try and encapsulate the entirety of the issues herein, I'd say the 1st thing you must decided is what caliber, and then pick a platform from there. The opinions on caliber choice are endless. Boston T. Party summed it up best when he said between the three BR calibers (.223, .308, 7.62) only .308 can be relied upon to penetrated cover. Take that for what it's worth, cuz any of those three placed directly between the eyes do the trick.
So like I said, instead of a fully tricked out AR or M14, I'd go for the "stock combo pak": a stock Ak-47 ($400), an AR ($650), and either a FAL ($950) , or an M14 ($1K) and have a blasty blast learning them all.