Arch is a pretty good one if you want to control and tinker. I have personally found it to be very reliable over the years, and the AUR is exceptionally powerful (although you NEED to review your PKGBUILDs, there's nothing stopping someone from putting malware on the AUR again). The packaging format is so simple and easy that I actually build a few performance-critical packages locally so I can tweak compiler flags (gimmie that -march native).

Nix is cool and kinda crazy, but honestly? I'd hold off until you're comfortable with Arch. Same with Gentoo.