>>64285865
PSA lower or Anderson with a CMMG lower parts kit that doesn't include a trigger or pistol grip.
if you're not looking to break the bank on a trigger get the "EPT" trigger from PSA. It's a polished milspec trigger for about $30 and companies like SOLGW often rebrand and up charge for them.
Lastly you don't need to break the bank on a "special" buffer tube assembly. get a milspec buffer tube and carbine spring and a H1 buffer(this works with most setups and makes for soft but responsive shooting).
goodluck out there anon.