So I just finished watching Golden Boy (1995), since I was curious about it and was very often recommended on various lists of retro anime to watch. It turns out that the show is obnoxiously horny, reaching "I can't believe it's not Hentai" levels in Episode 5 and that the show revolves around this seemingly incompetent dude that basically thinks with his genitals and always ends up getting the girl. The comedy is also basically 90% sexual and with such a setup, you can't really expect much else than objectification of women.
The animation quality is neat and the ED song is catchy though. 5,5/10
The above description might sound familiar if you've watched Great Teacher Onizuka (1999), which is similar in concept, except it includes a pretty good story and interesting characters. Unfortunately, it also is obnoxiously horny (which makes it creepier than Golden Boy due to the setting of GTO), is very ableist towards one of the students of Onizuka's to the point where episodes centered around them become unwatchable if you have a single ounce of liberatory ideology in your head and the show has some really bad filler episodes.
7/10? Sure. 8,69/10, like the MAL rating says? No chance in hell.
I don't really have examples of underrated shows or manga that are noteworthy enough to warrant me complaining about unfortunately.
Teppu is a manga about a couple girls who do MMA, and it's really freaking good despite nobody I know having heard of it. The story is complete too so you can look forward to it having a conclusion instead of going on forever.
Hajime no Ippo is about a kid who becomes a professional boxer, and is the gold standard sports manga/anime despite never quite getting the following it deserved.
Well, that's because it's basically a spiritual successor to Ashita no Joe (1970 - Season 1; 1980 - Season 2), which was huge in Japan, especially among the left and the classic proletariat. (Megalobox is also heavily inspired by it) I guess in either case, it's because you don't really expect a sports anime to be this good. Similarly, Slam Dunk (1993) is one of the funniest shows I've seen, despite being a basketball anime.