I've been floating around the idea of making hobbyist games for newgrounds in JavaScript. Using JavaScript to cut out the middleman and take full advantage of the newgrounds API. But there's like a dozen engines like phaser and rest. Which ones are worth using?

All of them are worth using, I don't think there's one that's objectively superior to the rest if you can even measure that. It more or less depends on which one works for you better than the rest, or which one grabs your attention more than the rest.

I used Phaser for a while and it was decent but I would probably have a bit of a difficult time using it for larger projects; others recommend using LittleJS (s/o @KilledByAPixel) and yet some others prefer engines whose names I can't recall off the top of my head.

I’ll be the one to vouch for Phaser 3. It’s fast, flexible, and can do a lot. Look through the many examples to get an idea of it’s features. The last major version was released recently, so you won’t have to deal with breaking changes from here on.

Oh, and it has the advantage of having an unofficial, optional and (somewhat) non-intrusive IDE, Phaser Editor. Once you start wanting visual tools for UI or whatever, you’ll be thankful that the option is there unlike most frameworks.

Phaser is the most powerful for 2D games

Kontra if you want a lightweight Canvas engine

LittleJS which is same as Kontra but it uses WebGL

Three.js is easier to get 3D games up and running

I recommend playing with Canvas and/or WebGL APIs which will help you understand JavaScript graphical potential and understand everything those engines offer.