too many TBH
1) Costco Citi Visa because Costco made me get it. I think Costco automatically charges our yearly membership on it, but I'm sure they could do it other ways, like add it to our bill next time we shop there (we give them way too much of our money). We never use it otherwise, even though in theory it's the best card to use at Costco. I don't really want to have to think about what card for what purchase, and my wife is even worse. I recently learned it has no foreign transaction fee, so it may become my backup international card. This is one card I may want to look into more, it might not be that big of a deal to use it more when paying at Costco. Also my wife tells me we sometimes get early access to concert ticket from Citi with this card.
2) Amazon Prime Card Amazon probably gets our next largest chunk of money after costco. It's set up as the default card when buying on Amazon, so it takes no effort/remembering, and 5% cash back is well worth it if you are a prime member. My wife never remembers to use it when shopping at Whole Foods, but it's not a place we shop much at anyway
3) Chase Sapphire Preferred. This is what we pay "everything" with. The one that gets taken out of the wallet, the one that's programmed in Google Pay, the one we give for non-amazon online orders, utilities, etc... If only we could put my kid's college tuition, our mortgage and taxes on it! We have a couple of recurring expenses that either don't take credit cards or charge too much for using a card, so those get paid directly from a checking account, but this is the one that we tried to consolidate points into until about 6 weeks ago. It's also been our main travel card (travel is part of "everything") and is the must-use for car rentals because of its better rental coverage. We've taken a few significant trips either buying flights/hotel through points via the Chase portal, or transferring points to United. this card also has a very generous credit limit, the kind you're in trouble if you ever reach, unless you found a way to put a car on it without extra fees.
4) Citi Double Cash Mastercard. After doing some math, I realized that the mile-per-point or 1.25c per point from Sapphire was not ideal for us. Getting 2% back would be a higher return even if it doesn't feel like you're traveling "for free" as the points card. But then I ran into a number of drawbacks with the Citi card, including foreign transaction fees and other (minor) headaches like its initial credit limit is too low. So this card will go unused in a few weeks when I get my Fidelity card
5) Fidelity Visa. I'm hoping this will become my "everything" card, get 2%, and allow ourselves to look at this 2% as "free travel money". I will likely not actually leave it into an account to use for travel, but will simply use the YTD statement to decide what spending "doesn't count". We'll see, I just applied and don't have the card in hand too. I like the ease of application (instant) and generous initial credit limit,
6) Mileage Plus Gateway. This account has been switched between different cards with United Mileage Plus, but it's my oldest account by far. It's got an insane (for me) credit limit, and it's only used for a $1.99/month recurring charge so that it doesn't get closed for lack of activity
7) Credit Union Debit Card. Used at ATM to get cash, which I almost never do, unless I'm traveling, in which case that's how I get my foreign-currency cash
8) Kohls credit card. In my wife's name. She gets some kind of perks/cash back when purchasing at Kohls so she's keeping in. Not used much. Platry credit limit.
10) HSA Mastercard for medical expenses out of HSA. Locked in the safe and never used, I use my HSA for investments.
I may eventually close the Sapphire Prefered, but it has a nice large credit limit and could hurt my credit score if I close it, so I may keep it and use it for car rental despite the yearly fee. It is the only card I have yearly fee on. I should also reserve a hotel once a year to offset get the $50 cashback to offset the $95 fee
One disadvantage of too many cards is that looking at my "everything" card was a good barometer of how much we're spending this month. Not so much once it gets diluted across multiple credit cards. But I started using Personal Capital/Empower to track my accounts about 2 years ago, and I do think the budget feature is useful to aggregate all cards (and direct from bank account) expenses into one view and one "better slow down, we're spending a lot this month"