I would put them right behind Amex and US Bank.
I've only had two experiences with Citi credit cards. They used to offer 25k secured mastercards with a 4% cd. Gf and I got one in late summer '09. In early '10 they limited cash advances to 5k and, coincidentally, dropped their max on new cards to 5k. That Spring my mom had a stroke and I found myself desperately trying to find an air ambulence to take her to my home on the West coast. After finding one I agreed to charge 20k on my MC and write a check for the rest but the card was declined. I called Citi and explained that I was declined for no reason on a secured card well below my CL. The CSR could see the decline and couldn't make sense of it so she immediately escalated to a CSR who could actually watch the CC activity and see the decline real time but they still had no idea why. They called in someone who determined it was the result of a banking policy change (probably related to the other 5k change?). They tried to use a manual authorization with the ambulence service but they were a small op and had outsourced the CC processing to a third party who couldn't take the manual authorization. Citi then went and changed something on the account "so it would go through normally" and waited until we verified it was approved. Subsequently, I've had a couple other occasions to run more than 5k charges through it and their have been zero issues.
I found Citi CSRs and techies friendly and quite diligent in addressing an apparently unusual problem.
The other experience was PCing the card above about a year after it was unsecured. Changed it to a WE MC. No pulls or any questions for that matter.