i'd take a Dell over HP any day!
I have no real preference either way. We use an awful lot of HP and Dell laptops and desktops at work, all much of a muchness. HP keyboards are definately stronger 
Both seem to suffer the most failures with disks and optical drives, which is to be expected. Neither better than other from that point of view, as they use the same components.
My HP Elitebook is the most unreliable laptop i've had, not to mention HP support, which have had it for nearly 3 weeks now and still waiting on parts 
Looking at what Ireland pay is though, its average is £5k more than here 
No wonder Dell are shifting production to Poland!
Which is probably where your HP is right now

Never had supply issues for parts for either brand for warranty repairs to be honest, guess its luck of the draw on the day.
Though, IIRC, your screen was abused, so if they are repairing it for free, not sure I'd rock the boat too much, if you catch my drift

I do remember one daft one with Dell - I rang them when the mouse buttons had, errr, come away from the rest of the laptop

Agent: "Hello, my name is blah, welcome to Dell support, how can I help you" (after the usual BS with Service Tags etc)
Me: "The mouse buttons are hanging off the laptop"
Agent: "Ah, OK, I understand. Can't you start the machine in Safe Mode"
Me: "Eh? What the... ...OK, hang on a sec... ...OK, I'm in Safe Mode"
Agent: "Is the issue any better?"
Me: "Nah, the mouse buttons haven't reattached themselves to the laptop"
Agent: "OK, sound slike it has a hardware fault then"
All fixed the next day...