Personally? Devilman vs Mazinger Z. It's amazingly animated especially for the time, the blu ray of it makes look real crisp. Also I say the action is split a fair amount between devilman and the mazinger cast.
Here's the torrent if you want:
https://www.bakabt.me/torrent/180658/mazinger-z-tai-devilman-mazinger-z-vs-devilman-bd-720p-m74
>>15765258
I love the part Devilman does absolutely nothing while Mazinger easily defeats his most importatnt enemies in a matter of seconds.
>>15765258
The best is Mazinger Z vs. Ankoku Daishogun by a mile. After that I'd go with UFO Robot Grendizer vs. Great Mazinger since they actually get to fight and it's pretty fun.
Devilman vs. Mazinger is is alright but I disagree with your assessment, Devilman is jobbing the entire movie.