I'm assuming you shoot more telephoto than wide angle otherwise you would have mentioned the wide angle zoom in your list here. 16-70 is the ultimate walkaround zoom IMO - super sharp and contrasty. Give it a try at a shop before you buy though to see if the difference over the cheaper zooms is worth it to you. The 18-105 is also supposed to be quite good, though I'd prefer to switch to a tele lens at the 105 end of the range (70 is plenty in a walkaround zoom). An alternative thought would be to choose your standard zoom whichever it may be and buy a teleconverter for the 55-210mm. A couple posters here have had success with the Sony VCL-DH1758, and shown great results, at least to my eye. I think you might need a step up/down ring to get it to mate with the 55-210 though.