Is GTA Online still worth playing in 2019?

GTA Online is filled with hackers, I suggest you download something like FiveM tho.

can be fun with friends but only worth when new content comes out rather then constantly playing as your main game

There will be life, but whether someone will play is a good question. A lot of hell, FUR cheaters.

Absolutely, dwindling hacker population aside, great RP, IMO itrivals Gmod in a lot of respects, as far as the physics engine goes. Its a better platform for RP than most.

There are alot of modders, but sure it can be fun some times

If you play alone it isn't even worth the effort.
Otherwise if you have friends willing to play with you it's a good option for having fun a few hours.

I only ever go on online now to see new DLCs, it's not really that fun anymore and I think we're due a new game really.

Nah, actually FiveM is better than gta online, gta online has so much hackers, but if you want to play with friends then create small local server

only if you want to get killed by every cheater on the server. there is so many hackers/modders now