Delta AmEx and Southwest VISA. I’m sure there are better out there but those cover the closest airports to family for us, and most years we go back at least twice (alternating Thanksgiving/Christmas plus once when the weather is actually nice and our adult friends aren’t tied up with their extended families). Neither lets miles expire with the CC (basically why I keep the SW Visa instead of the Costco) so with not traveling this year next should be pretty well covered.
I was using my Jetblue mostly, but not anymore. I now mostly use my Chase Freedom for the cash back. I also have an Old Navy card for when I shop there, but I haven't shopped much lately.
Costco VISA. It’s fine. My biggest complaint is that you can’t transfer the cash back to your bank account or request a check or pay your bill with it. Instead you get a paper voucher you have to bring to Costco which seems a little outdated and annoying. Especiallly because our cash back amounts are super high as it’s our main card. We bring it in and they give us cash which I then deposit. It’s a bit of an ordeal.
We also have the Costco VISA. You can take the voucher to customer service and they will cut you a check which we then deposit into our bank account. It is a bit of a hassle, but we also use it as our main card and it's definitely worth the trouble.