I have a Core 15 lower part kit in my rifle and I think it was a step up from the average milspec as far as the fire control group part of it.
The sear faces were baby skin smooth and not at all remotely rough, it has a very smooth trigger , others I have seen since have tooling marks, nicks and things that confirmed to me the Core 15 group was a little nicer..... and coming from me that's good because I am OCD about triggers.
I would buy a rifle from them without a second thought.
Thing with AR's mostly all the same specs , so much so that you can take a PSA bolt, put it in a Rock River carrier and put that in a Noveske upper, put that upper on a Bushmaster lower and shoot 1 MOA. Where some of the differences come into play is materials used, some companies skimp as I found out along the way. Pay attention to the materials used in the parts you buy, it makes a difference in longevity of function.....depending on how you treat your rifle and how much you shoot it.
You say now you might go shoot every now and then earlier in this thread, that will change, especially if you get and AR....especially especially if you build your own.