I'd prefer them staying true to faction but due to races changes and convenience / cost this is no longer the case
In my case, all my characters are part of my main's clan, as she's a super old vampire and definitely has the funds to have a big, multi-race clan that all help out in their own way. I used to prefer race/alliance being lore friendly but then thought, eh, I'd rather they just all be AD since most of the clan are khajiit anyway. I didn't have the "any race, any alliance" bundle until only recently so I just ignore the alliance they are ingame.
I only recently got Any Race, Any Alliance so I was locked into the usual choices for most of my time playing. I would probably follow that most of the time anyway, but when I went to create a DK for PvP and fight for DC way back then, I ended up with a Redguard and that isn’t ideal. I didn’t understand racial passives at the time.
I prefer the races of my characters staying true to faction
My only character is Imperial (as always in all my TES games for the past 25 years), so I've never belong to any faction from the start. But I chose Daggerfall Covenant because it stands for the restoration of the Empire.