Question as to what to get. . . .AR upper

[Orion_VTOL]

I finally got an AR lower, and now would like to get an upper. Here is what I'd like to eventually do. I'd like a short range upper in 16" (such as a Bushy Dissapator), and a longer range 20" upper with a stainless steel, which I hear is supposed to be more accurate. As far as the 16", I'm pretty set as to what I want. But for the 20", any suggestions?
Also, which one should I get first? I already have an AK for short range, so that would lean me more towards the 20".

Thanks for the advise.

 

[George Hill]

Moving to Rifles