Dino and Gajim both crash frequently on Wayland (Sway in particular) due to GTK issues that I'm not expecting to be fixed any time soon. Gajim also gets very slow the longer it's open, can't recall if Dino was the same. Dino also has the usual GNOME-y issues of being over-simplified and lacking in customization and features. When I changed from Dino to Gajim I was shocked at all the stuff I could suddenly do, was weird to think both were XMPP clients.
Something with Gajim's features but using Qt would be pretty great potentially. GTK stuff also often has this horrible thing where it fades the window when unfocused, which gets really awful and unresponsive when things get laggy, also ruins screenshots. Never figured out how to turn it off. Part of the theme apparently, but GNOME also doesn't want you customizing/changing your theme. I'm just using Adwaita-dark usually.
Matrix clients aren't great either, but overall Nheko gives me less trouble and pain than Gajim, using both daily. irssi (IRC client) is kind of my gold standard for stability/performance/features with weechat being mostly okay too.
If you're an irssi/weechat person, I use poezio as my primary client (and profanity is another console client, but I've never tried it). Obviously console clients lack some features (calls, avatars [usable ones, anyway]) but it does the job for me. I do use a Conversations fork on my mobile for communicating with family while I'm out and about, as it's nice to have calls and such then.
Dino.im crashes too frequently for my tastes. It also doesn't have an official Windows version. Gajim looks outdated and the update procedure broke several times (I know the authors are working hard to modernize it though).
iOS story is sad. Family used Snikket (thanks for your work on it) but it still dropped notifications even after following with issues and Prosody modules needed. (Monal seems to be okayish now).
Even Conversations.im seems stuck. I know everyone has their favorite missing feature but for me no reactions is the biggest.
Yeah, Pidgin has fallen behind significantly with regards to modern XMPP compliance. The developers are still working on Pidgin actively, but the focus is on a big rewrite of the foundations right now (3.0) so they can more easily support modern IM features.
I wish them luck, but considering their lack of manpower, by the time 3.0 comes out for "modern IM features", we'll probably have telepathic computers.
I was there when they had the famous video-voice branch.
Source: I use XMPP and Matrix daily.