I'm sure it's not a solo, but the end of April Ethereal (7:34 approx) is my favorite. I get chills every, every single time, tears in my eyes, the whole emotional bit.
i want to congratulate these guys for making possible to answer this kind of question about opeth..
i only think about it 5-6 seconds and there were more than 5 songs...it's impossible to choose a best..that's why it's opeth.it's the best itself....