it somewhat depends on if you are using mods, and which ones. There are a lot of portrait packs out there and a lot of them overlap on some level now, either in duplicate portraits or updated labeling.
to keep it simple though, i would download a few different packs and see what you like, browse a few of the packs before you integrate them by using file explorer and just browsing the files.
my pack is setup for Arrics Mod and even has the expanded races (optional toggle in the mod). I've tried really hard to add a variety of portraits and expand on the ones that felt empty. the downside to my portrait pack is that you will need to integrate a males body pack because I've scrubbed mine. (debating putting it back but the portraits were kinda trashy)
overall here's what i play with:
Mods:
Arrics Mod
--this mod just makes the game so much better.
Ankmairdors fix
--fixes so many bugs
(*constants* just puts itself in your mod files after one of these 2 downloads) follow instructions on the other mods.
Portrait Packs:
*****Erase the original bodies, and portraits folders in the base game****
Guests Portrait Pack Jan 2025
*there's a file for males and even a special file called 'perm chars' that you can adjust/assign on your own in game.
(i would recommend the 'buff dudes' pack to fill out a lot of the male portraits. they are much better then the original files in my opinion.)