I don’t hate flatpaks, but flatpaks require more disk space than the same apps from traditional repositories, and they only support a handful of the most common default themes. Since I only ever use older and slower computers, my disk space is limited, and I like to rice my desktop, I personally avoid them. But your use-case may differ.
KDE, because I’m too lazy to switch back to XFCE, which offered every feature I already use in KDE except without the stuttering, the bugs, and the update cycle that breaks things way, way too often on a rolling release distro.
Or openbox. My old laptop has openbox, but that’s more for screwing around with EWW than doing day-to-day things.