The joker is not a dceu movie and the dceu does not have more varied tones or story then the mcu.
The dceu tones are either dark,light or somewhere in the middle just like the mcu.
The mcu tends to have more varied light tones then the dceu however.
Of course the dceu darkest films are darker on average then the darkest of the mcu films so far and the lightest tone dceu films is not as light as lightest of the mcu films.
All vary in tone but my point is the mcu has more varied story and hero types.
You can't find magicians or sorcerers or superheroes becoming small or huge in the dceu so far,so that's my other point.
Anyway all these above makes the mcu films more varied then the dceu films.
Now it looks like the dceu will have more varied types of stories,hero types and maybe more varied tones down the road but the mcu is still ahead of the dceu when it comes to diversity of films.