I much prefer to use my laptop, because I have everything I need on it, and I can take it with me everywhere I go. But I would have to say that my desktop is an Acer Aspire that I've had for over 5 years, and it has stood the test of time. While I've had to replace my laptops several times over the years, my Acer is still working as well as it did the day I got it!
Laptops are very convenient but fragile at the same time. In my case though, it has been the opposite. I have had to repair my desktop several times. My laptop had stood the test of time until it was stolen last week.
I have a dell desk top it is 7 yrs old with no problems at all, I love it. Paid a small fortune so hope it last another 7 years. My lap top is a sony which runs hot but so far has lasted 4 years....I'd love to experience the new chromebook now and think that it would be my favorite!