I like them for convenience, I don't like them for customability, possibly just because I don't know enough about them.

No, because I don't have a very powerful computer

Even if I did, I would still prefer to have native applications because it would be more permissive

Theoretically I like the idea but in practice too many bugs, too much disk space, not really clear how to change font size for example... and after all that, some apps are not in flatpak. It is not ready for me yet.

almost all my apps are flatpaks

On my main PC I use for gaming I run Arch and prefer native packages whenever I can use them. I'm quite happy to have this one computer by a hobby project, and native applications just make more sense on something as up to date as Arch when they're available. I have started to prefer Flatpak over AUR packages though. The AUR is pretty overrated, in my opinion.

On my laptop and anything else I install Linux on I usually just use LMDE, and I'll often prefer the Flatpak, just because it's way more up to date. There are some apps that Mint keeps up to date native versions of, and there are some apps that come preinstalled that I just don't care about having the latest version of, but for everything else I usually just download the Flatpak.

Flatpaks are okay but they take too much space