Amex and Discover are my longest held cards, save for some super shitty Capital One Visa cards I just keep open to pump up my average account length on my credit report. I used to use my Amex exclusively, but for the past few years I've been using my Chase Freedom due to the 1% constant CB, quarterly 5% CB in certain categories, and since I'm way too lazy to use different cards for different things. My Amex is an old blue with 1% CB on everything. Also, Amex did away with statement credit for my CB, which sucks.
Amex has great customer service, though, and they occasionally have some decent deals on their card member exclusive statement credits. Shit, right now they have a $5 back on $25 or more at Papa John's, which is pretty useful IMO; since they are statement credits, they just stack with everything. I also had them lower my interest from like 19.99% to 13.24% in like a 2 minute phone call without any issues a few years ago after I hadn't even been using the card for a while. I'll probably snag another card with them in the future or convert my existing to something else.
Discover also has awesome customer service. I use my Discover as a balance transfer card, and they regularly seem to run 0% for 18 months with a 3% transfer fee. Pretty handy since all of my other cards are 0% for 12 months with a 5% transfer fee. I am confident that once I get all of my old college CC debt finally paid off, I am going to start using my Discover for purchases since it also has rolling 5% categories.
Most of my experiences with Visa cards has been mediocre, save for the Chase card I use every day. Ranging from membership fees, to shitty rewards programs, to higher rates, more fees, automatically closing accounts due to inactivity, and CS that flat out lies. Granted this is probably due to them farming out their brand to anyone that wants to offer a card and those specific companies, it's still their fault for having a hands-off approach to their brands.
BTW Capital One sucks balls. I am probably closing out my two old ass cards with them in a year or so when my average credit length gets a touch higher. Good thing there is no Costco in my area.