I sometimes prefer Flatpak over AUR, because I do not trust everyone on the AUR to run scripts with root rights on my system. At least Flatpaks are a bit sandboxed (even if the sandbox is an illusion) and the programs don't install and run with root rights. Sometimes the Flatpak is from the original developer and the script in AUR is not. Or the AUR script is not updated well and often enough, unlike day one Flatpak updates. But Flatpaks do not integrate well in your system and applications can look out of place too. There is a lot to consider, besides what you already mentioned. I use both, prefer the AUR in optimal cases.