There are several previous Q & A's and also hubs on this subject that I've read that you might want to read for some detailed pros and cons of each.
To me personally, it's all about the cost. You're likely to pay 3 times as much for the Mac as opposed to the HP. My 18-year-old daughter recently bought a Mac for college for a thousand bucks. I tried to talk her into the HP or Toshiba or whatever, but no, she had to have a Mac. Hey, it made her happy.