I prefer arch because I prefer simplicity. I prefer an additive approach to setting up my system rather than a reductive one. If I start with a distro with many packages I don't need, I'd have trouble figuring out what to delete. Arch Linux comes with very little initially and I can always add packages as I please. Additionally, installing literally anything is so easy on arch; the AUR has the best selection of packages available anywhere. And finally, installing arch is far easier now with the arch cli installer that is included with all the arch ISOs now!