ReZero and Twin Star Exorcist are both pretty good.
I've been listening to https://www.youtube.com/watch?v=cuH10m7fkoI and they didn't have much good to say about ReZero. I just watched some and it seems ok. I should probably watch some more. Twin star looked really generic from the promotional art I've seen of it so I haven't checked that out yet. I haven't seen anyone give it a recommendation yet other than you.
Mayoiga has great potential as a comedy. They're also obviously (and hopefully) going to die one by one. No other reason to have such a huge cast! That will be fun.
Except Lovepon and Hyouketsu-kun, those two have to survive until the end, because they are the best.
Crackpot theory: Rapper dude could have been killed by the bear or whatever else is out there. But what if he was killed by Masaki and her story was really a lie?
Here's a list of the good stuff (imho):
Re:Zero: boy transported into fantasy world... with an interesting twist. It also has some very good dialogue, character interactions and action. The first episode is double length and a bit slow, but the second half should have your interest and so far it's only been getting better!
Kagewani S2: 8 minute anime, so the first season should take you about 2 hours. Its an excellent creepy/horror/atmospheric anime.
Kiznaiver: I'm still not exactly sure where it's going, but so far it's been a great ride, it's full of energy. It's about a group of people who get 'connected by their wounds'.
Kabaneri of the Iron Fortress: If you liked Attack on Titan, you may want to check this out. And if not, you may still end up liking it. It's basically Attack on Titan in a victorian steampunk setting with zombies and trains. It's also pretty stunning visually.
Bunguo Stray Dogs: It's about a group of people with supernatural abilities, the Armed Detective Company, who have to solve supernatural crimes. Has a nice mix of comedy and seriousness. I personally didn't like episode 1 all that much but found 2 and 3 very great, but it was the opposite for others so ymmv with this one.
And then of course there's also always JoJo, with part 4 airing right now (and it's great). You could in theory watch it on its own, but I'd advise going through the other parts. They are all pretty good on their own, and it's just cool seing both the artstyle, storytelling and powers evolve.
I watched the first two episodes of kiznaiver. I'm not sure if I like it. The shared pain thing seems kinda boring. I had big expectations since trigger is making it and it seemed like it was getting the most pre-season hype. I have never watched JoJo. I'm not sure if its for me. Seems really over the top. People really seem to love it though. I might check out the iron fortress show tomorrow.