It's what works for you.
We used to have a yours, mine and ours system. We had a joint checking account that paid for joint bills, and separate checking accounts that paid for bills in our names only.
Once I got pregnant, we felt it would be easier to combine everything, so we did. It's been an easy switch for us. Now we have a joint checking and savings, plus separate checking accounts.
We have ground rules about spending and what's fun money vs what's not, which I think helps avoid arguments. We also view everything as "ours." So even though he got a bonus last year, we used it to pay off my student loan.
Combining our accounts is helping us reach our goals faster.