MacBooks are great little laptops, and Apple offers a few different options to choose from. The Wirecutter likes the MacBook Air, but it also digs into the differences between the available i5 and i7 processors.
The trick with any laptop is balancing power and battery life, and The Wirecutter digs into exactly what that means:
The Macbook Air comes with your choice of a 1.4GHz Core i5 processor or 1.7GHz Core i7. The Core i7 adds $US150 to the price. According to AnandTech's tests, the Core i7 is around 20% faster, but has about 1 hour less battery life under medium and heavy use. If you find yourself doing processor-intensive tasks like video editing or photo editing more than once a month, get the Core i7. Otherwise, get the i5. You'll probably notice the battery life difference more than the speed difference.
Essentially, if you're more concerned about battery life, stick with the slower processor. Although we don't have specifics on other models of MacBooks, it's a reasonable guess that the same goes for MacBook Pros and Windows laptops as well.
The Best Laptop [The Wirecutter]