All the top tier animators left (duo cartoonist, ink pots, doubleWbrothers, etc.)
A good chunk of animators, musicians and PMV makers (Theelinker, OmegaOzone, Half of the Antology staff, etc.)
DWK and that other comedic horse analysis guy.
Tiarawhy when she makes content (Fucking never).
The only good reactioner left is Ratchet, and even then he's kinda lame.
Greg when he isn't having an autistic patreon-fueled meltdown (Nepotism adventures is kinda good)
Most of the OG pone youtubers left long ago or never make anything, Mr poniator, the FiW staff, Drowning in Horseshoes, 4EverfreeBrony, SGaP, etc.
And a few others like Fluffymixer got worse over time.
That's about it.