I'm a "just put the money back in the monthly budget" voter.
It's free money so I don't overthink it.
The reality is with all these bonuses (I do a lot of them, some quite small) is that the money is kind of floating in the ether: this account receives a bonus, then is transferred to another to get a different bonus, repeat ad nauseum.
I try to keep my main checking account that I pay my bills from as close to zero as possible, so I can transfer the rest to my slush/savings/emergency fund which then funds IRA/HSA/Solo 401K, and sometimes tax payments (property and income). The tax payments generally charge at least two percent to pay with a CC, so I only do that if the cashback is at least two percent or I'm manufacturing spending to meet a spending bonus on a new card.