Hm...
Probably one of the big ones I stopped watching semi-recently was Cr1tikal. His videos seem too focused on Youtube drama as of late; although he still produces some good videos, they're overall still too negative for me/not really my cup of tea. He still seems like a good guy, though, and I wish him the best.
AVGN's videos are ones I've mostly enjoyed, but learning about Mike's garbage behavior and beliefs has put me off the Cinemassacre channel. I think James is probably still a very good guy whose beliefs are mostly good and he is maybe willing to make a single exception for Mike because of their timeless f r i e n d s h i p or whatever, but...long story short, I'm kind of disappointed in James despite thinking he's still mostly good, and Mike is an asshole.
I drifted from The Runaway Guys over the last several years, though I still think highly of Jon and Tim as people. With Emile...well, although the comments were a very long time ago (we're talking years here), his off-hand comments on rape in TRG's playthrough of (I think) New Super Mario Bros Wii, and also on his own channel's Pikmin videos, I think, struck a nerve that never really went away, since I rather idolized the guy back at the time. No offense meant to anyone who likes him! I really hope he's grown as a person since then, but I can't help but have some reservations. But I really hope he's a good person who just says things the wrong way sometimes, and has learned from those experiences.
I kind of experienced an inverse of this thread topic over time with retsupurae: I thought their earliest videos were a bit too caustic despite being funny overall, but I thought they got much better and funnier as the years went along (though there were still some iffy comments here and there, but still much better than when they started). Some of their wrongpuraes (let's plays of bad/weird games) are timeless. Although retsupurae isn't making videos anymore, I am definitely still fond of them. I'm not sure where Diabetus went, as slowbeef still seems to be doing well and making content. Hope the guy's all right.