Probably Jack vs Hercules. Jack was amazing and I was tricked just like the people in the manga. He had a sad backstory and you can see how it shaped him. Hercules' love for humans was also interesting. The way people cried for him and hated Jack was also a moment that caught me off guard.
I'd probably rank the fights like this
Jack vs Hercules>=Adam vs Zeus/Sasaki vs Poseidon>Thor vs Lu Bu>>>>>>Raiden vs Shiva.
Jack vs Hercules was my favorite showdown honestly
It was the PEAK of my enthusiasm with this show... still enjoying it btw... I just stopped the moment Anime was announced... so I’m giving the anime a chance... if it was done greatly, I will try to stay away from manga
I could be bias for this one cuz Adam is my favorite character from the series. The fight is intense, emotional roller coaster and Adam's death is absolute peak fiction.
2. Sasaki vs Poseidon
This was a very close choice. I could have put this fight as number 1 if it wasn't for Adam. Anyway, two of my second favorite characters fighting against each others, very enjoyable, Sasaki is goat. Poseidon is by far the best god. Love his arrogant and superior complex personality.
3. Jack the Ripper vs Heracles
Jack is by far the most developed character in the series, tragic backstory, very intelligent, unique fighting style. Heracles is ok, I wish we could see more of his other Labors that he haven't use.
4. Lu Bu vs Thor
Very hyped fight. Although I'm not a huge fan of both characters, the fight is still pretty good.
5. Raiden Tameemon vs Shiva
Raiden is a meh character but Shiva is goated. Shiva's backstory is good and his comrades trust him greatly. The fight is ok. Most people say it's shounenish but that's alright.