As has been said again and again: "it all depends. . ."
Unless you have a specific need for f/2.8 the new f/4 series makes a complete and usable kit with lots of overlap: 16-35, 24-120, 70-200. Unlike the 14-24 and 70-200 f/2.8 monsters, all three f/4's are very carryable. Yes, there's more distortion in the 16-35 than in the 14-24, but it's one of the sharpest lenses I've ever had on a camera and it takes all of two minutes in Photoshop to correct the distortion. Beyond the f/4 kit you probably want a prime or two for special jobs: maybe an 85mm f/1.8 for portraits, or a 50mm f/1.4 for night street shots. And you won't have to mortgage your house to buy this kit.