Parmandur
Book-Friend, he/him
I think the Class/Subclass mechanic really takes away the need for expanding the Class list too much: between the PHB, Xanathar's and Tasha's there are over 100 Class options, but nesting them makes them more manageable.I want more classes.
If it were up to me I'd split the Rogue at least 3 ways.
Assassin
Thief
Scholar
But I am a lot more creative in mechanical design than the average D&D fan. Even more than many hardcore fans. So I doubt my true preferences would ever catch one. That's whyI'm only gauging the one that existed first.
It's too bad that Themes didn't survive the Playtest, because a triple interlocking nesting may have helped scratch that customization itch a bit for folks.