So it seems that I've been watching part 3 of JJBA, Stardust Crusaders. Should I go back and watch the other 2 parts?
Hell yes. They're pretty much self-contained arcs (season 1 is two arcs) detailing the earlier generations of the Joestar family. You should watch them before getting too far into Stardust Crusaders.
And that OP for Battle Tendency ... all the OPs are good, but BT is a level of "fabulous" above all else.
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As for more airing anime:
Yami Shibai - Japanese Ghost Stories. Everyone should check this one out (it's on season 2 now). Really short ghost stories. Not all of them succeed, but enough do to freak the hell out of you in ~3.5 minutes of runtime per episode, which is quite an achievement.
Sabagebu is pretty decent, it's a Slice of Life / school / cute girls show, but it's also hella violent, constantly breaks the 4th wall, and is very genre-savvy: it constantly sets up relevent genre tropes only to subvert them. It basically has 2-3 mini-stories per episode, similar to Squid Girl or something. Not really an "enlightening" anime, but I'm enjoying it for some laughs.
Majimoji Rurumo is about this witch Rurumo who is very cute and clumsy and doesn't know how to deal with the human world. She is really adorable. Unfortunately she's basically a side-character in her own show, which is a cliched harem anime. The scenes with just her are great, but they're rare and most of the time they have to focus on the "main character" who is the run of the mill pervert highschool student. This coulda been another "Squid Girl" if it just focused on Rurumo trying to navigate modern life, or had a female character as her foil. rather than a harem MC's cliched problems 90% of the time.