this is a question with varied answers, all of the above are good but it depends on what you are willing to do.
Hoxton Breakout is the highest RAW payout, meaning you only have to beat the heist to get the reward, but you dont get any additional loot (bar some ATMs on day 1)
Cook off or white XMAS both work as infinite loot sources but, simply put, its challenging and the initial payout is low, you need t stay a while to get much out of it.
Golden Grin and Framing Frame are very good for the payouts in a short(ish) time, if you are sneaky.
Ideally, GGC for stealth and Hoxout for loud. Hoxout DW pro will take about 40-60 minutes and pays out about 12 or 14 million into your offshore account