I've been using macs at home for over 15 years and found it to be very enjoyable to work on so I would recommend the macbook. As for the Dell, there have been some reliability issues over the past few years. The company that I work for used all Dell computers but the failure rate and technical issues were very bad. As a result, when the contract was up, they switched to HP.
Consumer Reports rates Apple computers #1 in every category they are in and have done so for over 8 years or more. They are number one in reliability, service and usability.
The best machine is the Mac Book. This is not only sleak & stylish it is also very thin and light so transportation is convenient. I think the sound quality of the Macbook is superior and they seem pretty durable. The Dell is not a bad second choice though, so which ever way you go you should have yourself a pretty decent laptop.
I love MacBooks. However, they are quite expensive when compared to other laptop such as the Dells. That would probably be the only drawback for me. Otherwise, Apple all the way!