I was a Arch Linux fan for at least 5 years. Tried all the main ones except gentoo. Kept coming back to Arch. But now I'm one week into using NixOS. I don't think I'm ever going back. It has completely blown my mind, and fixes every minor thing I didn't like about arch. Mainly how package dependencies work. I'm sure there will be a downside somewhere, but so far the only issue I've had is just trying to learn how to config everything.
TLDR: NixOS. I don't know how I didn't know about it till recently. Seems like it would be a lot more popular than it is.
Back when I was on NixOS, my main bugbear was that the Nix package language is pretty esoteric. I have some experience in packaging on Linux, so I thought I would be able to be able to put together at least a minimal package. No such luck. You how Haskell has a reputation for being difficult and full of burritos? It was like that, but the burritos were packages.
That makes sense. Maybe the nix language itself is the downside. I've have never built a package or anything like that before. I've only done web development and still pretty new to it. I like the concept of functional programing languages like nix and Haskell. But the only language I really know so far is JavaScript.
And the best part is: When you're done trying it out and like your setup in the vm, you can simply copy your configuration.nix over to the real machine ;)