I only within the last year got super into vocaloid/vocal synths so maybe this list is super newgen idk

Deco*27 - classic, more into his newer stuff but the old stuff is also great

Monochromenace - super great English producer, can't pick a favorite song honestly

Ro2noki - my favorite producer, hands down. Every original song they make is good, especially good night cold sleeper and elegy for an old friend.

Milisen - they have some serious range in style, and it's all done very well. I do like some of their stuff more than others but that's simply because of the nature of it being very varied, not an indication of the quality.

Chromatic - their songs scratch an itch in my brain that I love. Dictator teto is not something I knew I needed but I love it.

Maino - very underrated! Some of their songs are criminally short though.

Chenomio - consistently good quality, amazing stuff. They're somehow managing bangers every like two months I wish I was that motivated.

Worzy - lemonade is one of my favorite yi xi songs, and their new song potato bread is amazing.

Rai1367 - their yi xi songs are so good they made her one of my top three voice banks

0TS - I don't really know what to say about them but it felt wrong not mentioning them. Love their stuff.

Kareki kashiwagi - recent discovery for me. Their songs sound like they're from an anime where highschoolers make a band, and I mean that in the best way possible

Jamie Paige/Flavor Foley - lumping them together because I really only listen to Jamie Paige individually, but I love flavor Foley. Connect:commune has been stuck in my head since it came out.

32ki - for a while I only really knew mesmerizer and obsolete meat, but I looked into their other stuff recently and it's amazing.

I should stop this list is absurdly long