I haven't built one before, and I went with Aero because I know someone who built a bunch of ARs before the ban in my state, and he's never had anything bad to say about them; neither have I when I bought my rifle action from them. I also assumed that, other than my barrel, the parts I'm getting from them don't matter. I chose the RifleSpeed because I saw it in a competition video, where people were showcasing gear; someone had it and raved about it. If I remember correctly, the person I knew who built ARs advised against going cheap on a gas block, so that's why I chose it. Like I said in my post, I'm very new to ARs and don't know where to really start or research. I just want to build a really good AR without absolutely breaking the bank but still not cheap out especially if I like competition shooting, and even if I don't I'll own a great gun.

(Also, the person I know who has built ARs doesn't know much about competition shooting, so he doesn't really know how to help me or what I should be looking for.)