The difference, I’ve found, between HP and Cisco switches operationally is nill. They both do the job. Yes, they’re different but similar enough to not give you too much of a headache. In any event, once you get used to them, they’re not a problem. The CLI is mostly semantic; “Display” vs “Show”, for example, or “undo” vs “no”.
Then there’s the business issue and this is what swayed me from Cisco to HP. HP is not only less expensive, but the lifetime warranty is “free” versus Cisco’s pricy SmartNet.
I also just stacked a couple of HP A5500 switches and was able to do this with only one CX4 10GB cable. The last set of Cisco switches I stacked required two cables. And at about $400 per cable, this was a cost savings as well.