+1 to everything these superstars have said
Now my preferances are Vang comp everything:
Barrel: Hans sometimes has police take-offs that he will sell for cheap with the work all done. (Try to get one without porting, I shot mine without earpro=not good.)
Ghostring sight (his front sight is robust and well protected, and the front takes an AR front sight)
1 shot extension (handier then 2 shot extention and more robust the 2 shot)
Forearm has to be surefire (I like the less cluttered old school laser products one)
Stock, Hogue super short ( although I will be trying a magpul stock)
As far as side saddles go I like all of the well made ones, the Mesa Tactical 6 shot is good. I haven't tried the Velcro ones nor due I intend to they appear to be weak.
As it is late I can not thing of any thing else to add I will call it done.