If you could only keep one lens that you currently own for all purposes, which would it be? Go generic and stick with a 28-80 on a full frame/35mm or 18-55 on a crop body? Pay the weight penalty and go with a 24-70 f2.8? Keep it simple with a 35 or 50mm prime? Dedicated portrait lens such as an 85mm 1.8? Go pro with a 70-200 2.8? Do you absolutely NEED a macro? Looking back at some pics over the last couple of years, I might guess that I've used my manual Nikon 55mm f3.5 macro the most. Nearly all my for sale pics are with it and it sees some duty on most individual and couple portrait shoots. Plus it's 55mm on the D700 or about 80mm on the D300. I've thought about getting the Tamron 24-70 f2.8 VC. It's quite a bit smaller and lighter than the Nikon so it might see more use. I used to have a non-VR 28-70 2.8 Nikon, but that's a darn heavy lens to keep on there full time. Back when I shot more canon, i used a 70-200 f4 non-IS on a 5D an awful lot.