Bountyhunter - You make what you bring in basically. Think it works out to you getting half that person's bounty.
NHS - It's more about the roleplay, you get 12k every 15 minutes and 7500 per revive.
Arac - This is all roleplay and most people just do this for the spawn. You don't get a salary it's just dependent on how generous players are.
Police - A lot more action but you can't really spend your money on anything apart from Julies mouth watering crumpets. 20k every 15 minutes, bits and bobs for actually doing your job.
In my opinion, if you only care about doing money you should just focus on being a rebel and doing salt runs 'cause they're legal and I'm a police officer so I definitely don't condone drug trafficking #unlessyousharewithme.
NHS is always fantastic to join as it's good money and the role play you get from this specific opportunity is wonderful. It's personal preference really.