If I was limited to only 3 cards, I would definitely make them from 3 different financial institutions. I don't like having too many eggs in one basket.
In this year of the pandemic, I would go with:
Chase Amazon Prime
Amex Blue Cash Preferred
Citi Double Cash (AOD has too many hoops to jump through for me)
In a non-pandemic year, I would choose:
Amex Amazon Business Prime
Chase Sapphire Reserve
Citi Double Cash
If I had to choose just 3, it would probably be Discover It, US Bank Cash+, and Citi Double Cash.
@TattnallTrio wrote:Finger Hut
First Premier and Blaze MasterCard
Fingerhut kicked off both my credit journeys in life so much luv there
If i could start over and with NO cc debt!...
I would have take a Navy CR , PF PCR, and Discover
I see AOD in everyone's sig and it makes me feel left out. I am weary of CU's I suppose.
3 is tough but probably:
AOD: if it wasn't complicated to get and I was assured it'd never lose its benefits (why I don't have it already).
BCE: if I always had the option to go back and forth to BCP as it fit my needs
Chase Freedom: As when the categories line up, it's convenient to be able to earn cash back rapidly, even with my fairly restrictive spend
Can we also state the 3 we regret?
Capital One Secured: Garbo, never upgraded, never got a better limit. Better options existed to begin my credit journey.
Chevron Texaco card: Thought I needed to maintain one regular MC to improve my credit profile. I did not. Sync sucks.
Marvel: Chase Freedom Unlimited added the dining making this card irrelevent. Still remains a toy limit after 1.66 years. Only one in my profile below $5K limit. Oh and did I mention? Sync sucks.
Must garden until 2/1/2022 to hit my goal AAOA. 
@Anonymous
Chase Fredom Flex
US Bank Cash+
Amex BCP
...of which 2 of the 3 I still don't have and could quite possibly never will. 
EDIT: eek, I forgot AOD...man, limiting to 3 is tough. I guess it would be:
Chase Fredom Flex
US Bank Cash+
AOD 3%
