Two Worlds 2 has a much deeper magic system than Risen, there's endless possibilities in spellcrafting whereas in Risen you only have Bullet, Fire & Ice crystal for offense.
I prefer melee in Two Worlds 2 as well, it may be a bit easy after a while but at least it's fluid unlike the clunky mess in Risen. And unlike melee in Divinity 2 and the first Two Worlds game at least this time it is not a complete clickfest... you need to block and use your skills.
As for graphics, Two Worlds 2 blows both Risen & Divinity 2 away. Risen has beautiful environments, but the character models are horrible.
Divinity 2 for me is best when it comes to dialogue, voice acting & overall quest design. Story is pretty weak in all three games... amusingly all three have absolutely abysmal endings.
