Welcome to the forum! Glad you could find your way here. As far as Lower Parts Kits (LPKs) go I would suggest sticking with Aero for the Aero lower. They have very solid budget minded receivers. When I say budget minded I mean that they after an affordable product with great quality control and no frills. I would also stick with an Aero upper to match and standard parts kit for that.
The only thing I would say you should invest more into would be your barrel, BCG, and trigger. Plenty of affordable barrels from great companies like Faxon, Balistic Advantage, BCM. I would very much recommend a BCM, Sionics, or SOLGW for a BCG. Larue MBT is a very popular trigger and very well priced for a two stage.