If you're talking about overall and also factoring in security, then I would say Phantom Overlay (PO). They're not internal, but external though if that makes any difference to you.
Hasn't been detected since release and hasn't had any red trust factor issues come up. The aimbot might not be as strong as an internal one, but for an external, I don't think you can get it any better than it is. There's a lot of settings to adjust as well, so you can get it even more accurate, though it might look a bit sus depending on your style of gameplay. If you have even some game sense and aim, PO will make you look like a pro.
I would still say PO is best to be used for closet cheating though. They might not have a ton of features like other providers, but they make up for it with strong security and optimizing their fewer features. If you're looking for a rage cheat, PO isn't what you're going to be looking for.