Hello! First post, I saw this thread and it had been something I have been thinking about recently, as well. I am new to credit and I have not been as adventurous as some of the people I read on here as well as the Fico forums. When I began my credit process I started with a Capital One card, and eventually got an Apple financing card because at the time I was seriously considering getting an Apple product.
I changed my mind, and did not use the Apple card for almost a year. Barclays horror stories aside, they did not cancel my account, but in fact increased my limit, even after over 6 months of non usage with no balance. When I decided it was not a card I would probably use again I looked on their website and decided to apply for their Rewards card. I was approved for 4k. I shelved the Cap1, started using the Rewards heavily, and one day after speaking with a CSR they increased my limit to 6k (this was just a few weeks ago).
My husband started with a Cap1 card when he was 18 which he used and PIF faithfully. He switched to a Visa Venture, and basically did the same. He just recently was approved for the Barclays World Arrival (5k) and that will be his new card. Barclays has been very good to me, and I wanted him in on it as well.
Now when it comes to applying for credit we are fairly conservative. We love Rewards, and he is open to it if the deal is good, but we definitely do not like juggling a gazillion different cards, no matter what the benefits. So if we find a card that is better, we will generally switch and move all our business to that one card.
So I guess in that sense we are a One Card to rule them all family.
I use Barclays Rewards MC for my purchases.
He will be using Barclays Arrival once it comes for his purchases.
We both use PNC Cashback for our internet purchases.
Husband has a Bank of America Rewards card which is strictly for his father. He is the primary, his father is the auth user; our mothers are very self sufficient, but his father is on a VERY limited income, so we gave him that card for emergencies.
Husband also has an Amex Blue Cashback, which has never even been activated. He got it back in October with the intentions of switching to the Amex, but then he kind of tossed it on the desk and forgot about it. I have been meaning to activate it and switching our internet purchases to it.
I am the one who pays the bills in the household, and I like to keep things to a minimum. I don't like having to visit a whole bunch of card sites, and I don't like having to figure out which card to use this, or that for. I am ok with getting less rewards in exchange for simplicity.
That is my two cents. TL;DR:
One card for everything.