GTA Online - Do missions, "plan out" and carry out heists, earn levels and get access to more options in-game (Such as getting a Bussiness (Bank) , motorcycle club (MC Businesses-weed , cocaine, meth etc.), Bunker, Facility, Arcade, Warehouse (Smuggler's Run DLC stuff) etc etc) , also buy cars and luxurious items . The main catch of this game is unknown, you can set goals to yourself , but it's said money is the king of los santos. The catch is most likely to have enough money that you're bored of it and have nothing else to do (Gets really boring when you reach this level).
FiveM - If you're into roleplay servers, this is the game. Start out a new life, get a work, earn some cash and do whatever you wanted to - through roleplay! You can also do heists on some servers, which is even more fun when you have people with you, or you can live a normal life or fight criminals. Catch is - you can immerse yourself! Like if it is real life , but don't go too far out of boundaries!
Either way, you can play both like I did. I switch between them depending on my mood. Have fun mate! Hope I helped.