The MacBook Air line has always been about compromise--as I , the Air was initially appealing mainly to people for whom small size and light weight were more important than the features the Air was missing. But two things have happened since then. First, some of those missing features--an optical drive, for example--have become less important. Second, the Air's features and performance have been improved, , to the point that an Air no longer like a compromise. As a result, the Air is now Apple's core notebook and, by some accounts, the company's most popular laptop.

The 2012 MacBook Air models should further cement that position, as they're easily the best Airs yet. Thanks to upgraded processors and graphics capabilities, along with both Thunderbolt and USB 3--features still missing from Apple's Mac Pro line--for expansion, it's getting tougher and tougher to say the Air isn't a "full-featured" laptop. And you no longer have to give up a good chunk of performance if you want to go light: Thanks to flash storage, both 2012 Air models are competitive with Apple's current hard-drive equipped 13-inch MacBook Pro models (and the Air has a considerably better display). In fact, if you don't need a 15-inch screen and lots of storage space, it's now .

As for deciding between the 11-inch and 13-inch Air models, with the exception of the 13-inch Air's SD card reader, your choice mainly comes down to screen size. Yes, the 13-inch model sports a slightly faster processor, but the actual performance differences are small enough that those who prize portability can go with the 11-inch Air--a frequent traveler's dream machine--without worrying about what they're giving up. (If you do go with the 11-inch Air, I recommend the $1099 model over the $999 Air for the additional storage and the option to upgrade to a 2.0GHz CPU.)

I suspect, however, that many people want a bit more screen real estate, and it's only $100 to make the jump from the 11-inch 128GB Air to the 13-inch model--an easy decision if you need the space. I recommend the $1499 13-inch Air only for those who need a lot of storage space (256GB, upgradeable to 512GB) and the option for the faster processor.

Finally, some advice for current Air owners wondering if they should upgrade: If you bought a MacBook Air last year, the performance boost from 2011 to 2012 is significant, but it probably isn't worth buying a new machine--after all, if cutting-edge performance was your priority, you wouldn't have gone with the Air. But if you've got a 2010 Air, the 2012 models offer major performance improvements, and if you've got a 2009 or older Air, upgrading is a no-brainer.