I've only seen a few bits of the overall Mazinger family of mecha (not counting Getter Robo, because I'm a bit of a Getter Robo purist and like the versions of it that are less related to Mazinger better than the ones that are more related... though Getter Robo has my unending affection in all its forms), but out of what I've actually seen all of*, this short is easily the best.
(Side note: God Mazinger, the rather pharaoh-esque robot with the sword, had his own technically completely unrelated show, and from one episode of it comes this amazing clip. Also, I've learned [well after my initial investigations of this short] that the modestly ugly Mazinger lookalike with the assault rifle, Govarion/Gobarian/what'sitsname, is actually a construct created through its pilot's psychokinetic powers, which is amazing in its own right.)
Out of the broad family of Mazinger media, the next best part I've seen from one end to the other is Mazinkaiser SKL (not to be mistaken for regular-brand Mazinkaiser, who is terrible-and I know because I watched the OVA, thank you), which is a movie that can be found in its entirety on Crunchyroll and probably other legal streaming sites.
It's... still got some more-than-a-little skeevy bits (which are my biggest problem with regular-brand Mazinkaiser), but to nowhere near the same extent. Granted, the ostensible main characters are... let's call them boring as hell, but if you're just watching for ridiculous action sequences? This is a lot better than regular-brand Mazinkaiser.
*The best Mazinger thing was Shin Mazinger, which was ridiculous and funny and cancelled too soon for this world.
I'd link the time I embedded a video from it, but the video's gone. The video involved an animate giant robot** throwing his own severed arm at someone because he saw Mazinger Z's rocket punch and thought it looked like fun.
**Who was 1) much bigger than Mazinger Z, who could ride comfortably on his shoulder, and 2) was supposedly the mythological Zeus***.
Easily the best reinterpretation of that jackass ever, right?
***Considering that the Mazinger mythos involves ancient an extremely technologically advanced civilization popping up next to ancient Greece and having influence on Greek culture, that actually kind of follows.