I have the SCAR 16.
Pros:
Balanced
Not heavy
Simple take down for cleaning
Accurate
Robust components
Zero recoil
Tight fit
Exudes quality
1 in 9 Twist: Shoots 55 grain and 62 grain equally well. Can stabilize heavier rounds.
Monolithic rail
Front and rear sights flip down and are rugged and useful
Charging handle can be on either side
Folding Stock - weapon still operates when folded
Collapsible stock
Adjustable check weld/comb
Plenty of sling attachment points
Chrome lined barrel
Muzzle Brake
Chamber and bolt carrier group stay clean and cool
Bolt is slightly different that AR15 bolt and said to be heavier.
Cons:
Loud - because of Muzzle Brake
Charging handle is high enough that some optic mounts leave little clearance
P-MAGS do not allow bolt catch lever to lower correctly (and damaged mags or out of spec mags can do likewise)
Notice that I did not mention price as a pro or a con. Spend what you can afford to spend, risk what you can afford to loose.
I have only shot three AR-15's in my life. They shoot fine. I have never cleaned one. Since I have no training with an AR, the battery of arms, the way it functions, the location of the controls of the AR were not a selling point for me.
I have owned a SIG 556. If you are pleased with the AK world you might like the bolt carrier group of the SIG 556. The Robinson Arms XCR is also similar.
I will some day get an AR-15, most likely a S&W, Rock River, or similar.
During my research I emailed several gun reviewers that I felt are independent and would give me solid advice. My results of their recommendations are listed in order:
1) SCAR
2) LWRC
3) ACR
I asked them which the liked the best, which gun they wanted to shoot.
Good luck with your quest. I recommend you lay out your budget.
Consider the entire package, weapon, optic, sling, mags, and ammo, etc.
(This is from a $1200 AR to a $2500 Piston Rifle)
Weapon price $1200 - $2500
Optic price $500 - $1000
Sling price $35 - $120
Mags price $10 * 10 mags = $100
Ammo price $300 for 1,000 rounds
Low end is $2135
High end is $4020
Of course these are just estimates and guesses, but it all adds up fast. It is all just to illustrate things to consider.
Buy what you can afford. Set a time for when you want to make your purchase and then buy within your means and stay within the amount. Being too deep into something price-wise can result in extreme anxiety if there are any issues with any of the components, especially if the rifle has problems.
BTW: Here is the link when I was asking a similar question:
http://thefiringline.com/forums/showthread.php?t=457456