Given how many different Mazinger Z series exist, and how some of them had several versions, it is unsurprising the characters and the view fandom has from them vary wildly:
Kouji Kabuto is always Hot-Blooded. That is nearly the only thing all his versions have in common. In the anime series, Kouji Kabuto was an arrogant, sexist Jerk with a Heart of Gold and a Chaste Hero. However in the original manga he was less of a sexist and less of a jerk. He was more tactful, nicer -mainly to Sayaka- and was a bigger pervert (and he even blushed when Sayaka paid him a compliment). The Gosaku Ota manga, being an adaptation of the anime, stood halfway between both characterizations. Most of the fans's view is influenced by the anime version, so that is how they see him in spite of later retellings and remakes are mostly based on his original manga incarnation. Maybe the most weirdest version of all is the one from New Mazinger: he is a soldier lives in a post-apocalyptic, torn-war Crapsack World. He lacksHot-Blooded Sideburns and his hair is partially red. He is only known as "Major Kabuto" and no version of Sayaka, Boss, Prof. Yumi or Dr. Hell show up (then again, it was only an one-shot story). The Mazingerz Kouji Kabuto is more recognizable, but he has flashes of being a Totally Radical kind of teenager.
Sayaka Yumi was always a Tsundere, but in the original manga she was Type B and in the original series she was Type A. Her characterization in later versions varies between one type or another. And some fans think she was very stuck-up and bratty and more interested about showing off than saving the world, whereas other fans state she was simply an Action Girl had a very short supply of patience to deal with a loud-mouthed Idiot Hero and an aloof father cared for her but was Married to the Job.
The interpretation of the relationship between Kouji and Sayaka also varies depending on the fan. Many consider matter-of-factly they are the Official Couple, but some argue Kouji did not love Sayaka back. They base that interpretation on him teasing and mocking Sayaka constantly and showing interest towards any girl but Sayaka (Hitomi, Misato, Erika... even Minerva-X) and he was nicer to Maria in UFO Robo Grendizer. Of course the former group of fans are quick to point out most of shows used the Chaste Hero trope back then - depicting The Hero like someone who is too busy saving the world to get too concerned about romance-, he baited Sayaka because he WAS a sexist jerk -and not because he was not interested in her-, , the Belligerent Sexual Tension was an Unbuilt Trope back then, the anime series showed plenty moments where Kouji cared for Sayaka, the Go Nagai manga (that Is the original story whereas the anime is an adaptation) did way more obvious he liked Sayaka, and in the Gosaku Ota manga they DID kiss. And they remind Kouji was more mature when he met Maria (when the first series began he was sixteen. In Grendizer he was already nineteen) and she was supposed to fill SAYAKA's role. And let's not get started with the ones think there was Ho Yay between Duke Fleed and him.
Dr. Kabuto in the original manga was a Large HamMad Scientist with an evil-looking scar running across the left side of his face. He had never met Dr. Hell and built Mazinger-Z because he felt guilty of his grandchildren were parentless and he wanted to give them something to protect themselves (and he pretty much told Kouji he would be able to take over the world using Mazinger-Z). In the anime version he was a well-meaning, average-looking, kind scientist built Mazinger-Z to fight back the menace of Dr. Hell. The Gosaku Ota manga version uses that characterization, but later retellings usually use the original Go Nagai version. In Shin Mazinger he is a Crazy AwesomeMad Scientist. In Shin Mazinger Zero... he is a Complete Monster.
Boss is the Plucky Comic Relief to some fans. To other fans he is an unsung hero who always helps to the main characters and has nothing for his efforts in spite of some of his actions contributed to save the world. And depending who you talk to, he played straight or subverted the Hopeless Suitor and Stalker with a Crush with Sayaka.
Dr. Hell is a Large Ham and a Complete Monster wanted to Take Over the World to force the whole humankind to bow down to him, but in Shin Mazinger he was actually trying to save the world (although he thought conquering it was the proper way to accomplish that). Some fans actually feel Sympathy for the Devil, thinking it was unfair he worked so hard, scheming complex plans and strategies and crafting incredible scientific breakthroughs oinly to be defeated, crushed and humiliated over and over and over by a loud-mouthed, Jerkass Idiot Hero with a cool Humongous Mecha. People who knows about his Backstory also tends to see him like The Woobie.
Baron Ashura usually was completely loyal to Dr. Hell. But in the Gosaku Ota episodes he got fed up with Hell punishing his/her failures and Brocken mocking him/her, and he/she decided betraying Hell. In that storyline Ashura almost succeeded where Hell had failed.
Yuri, Sayaka's cousin and Bratty Half-Pint is regarded by some fans like an insufferable, unbearable brat. Other fans see her like The Woobie, a poor little girl yearns for attention because her parents neglect her constantly.
Tetsuya Tsurugi in the original anime was excesively prideful, prone to fits of jealousy, could not stand someone showed him up and sometimes he seemed more concerned about showing off than protecting mankind. Other versions of him, though, are less jealous -he retains his pride, though, and he does NOT like it when someone doubts or slights his skills-.
Jun Hono in the original anime was a Type A Tsundere, half-black girl. In the original Go Nagai manga she was a Type B Tsundere and she looked full-Asian. It is said Gosaku Ota drew her like a half-black girl, though, and Go Nagai liked the idea and her race was retconned in canon.
Kenzo Kabuto may be a benevolent but harsh The Mentor and a lousyparent... or, depending on the adaptation, one of the villains.
Duke Fleed was a HotBlooded hero, but in the anime he tended to be calmer and quieter when he was not piloting Grendizer. In the manga versions he is hot-blooded the whole time.