Listening to Mikael's death vocals is like eating well-prepared spicy food - sure there's a bite, and sometimes it even hurts a little, but it tastes so good.
But you can't just eat spicy stuff nonstop. You have to cool off. So you take a nice long sip of cool beer. Those are the clean vocals.
The best Opeth songs are the ones that balance this mixture correctly, that is to say evenly. So, to bring this analogy to a close, no I cannot chose between the two. Both are part of what make Opeth great.