I have 3 M4 style AR’s, now I am going for something different. I currently own a suppressor. Also I am not trying to build a high dollar rifle. Keep it at around 1K.
Option 1: M16A4 style 20 inch upper.
Option 2: Dissipator
Option 3: XM 177 style
Option 4: 10.5, 11.5. 12.5, etc… SBR
Option 5: Other, please explain.
I figured you need a full size since your other 3 AR’s are carbine variants.
Recce or SPR…
I’d go with the M16A4. No real reason for saying this other than I’d like to build one. I’d use a BCM upper and would probably go with a Daniel Defense rail over the KAC rail.
I’ve already decided on a BCM upper regardless of configuration. That is unless I can get a DD for a much better price.
oh, my !!! 
hands down, build the 20’’ service rifle, get a A1detachable carry handle, your set.
i have a mutt clone SP-1, and working on a lightweight middy gas, dissipator,
tuff choice’s , build the service rifle AND the dissy !!!
I’m goin with an SBR myself.
Double tap
SBR type rifle. Or a pistol build first and see if you like saving the 2 benjamins. As soon as I’m done building my pistol and it works like I expect it to I’m gonna start getting stamps. You do have a suppressor, so SBR/pistol build makes a lot of sense.