You can choose between things like flatpak or aur packages, but you’re gonna have to use pacman either way, since your core packages are still managed by pacman even if you decide to install most things through flatpak. Just wanted to point that out in case you were thinking of not using it at all anymore, cause it’s definitely not good to have your system get extremely out of date overtime. Having said that, it’s a matter of preference. The aur has more packages available, but flatpak has verified packages available, so assuming you stick to those, it could be safer. It also offers things like sandboxing. When i was on arch i only used the aur. I usually go with whatever has the most packages available or whatever is most convenient.