Larian Studios Forums Divinity: Original Sin 2 Divinity - Original Sin 2 - General Staves compared to wands are terrible.

Staves can take advantage of the "Opportunist" talent. Which can be quite big in some cases
With a stave, you can also attack from range (one time per turn, but if you are a caster, that's usually more than enough)

minor: If you put points in 2h instead of dual wield, you get more crit damage as well instead of dodge