I'm sending back my Tamron 28-75 f/2.8 and looking for a replacement. Option 1: Use the money ($400) from this lens to fund a similarly priced lens. Nikon 35-70 push/pull or Sigma or ??? Option 2: Also sell my Sigma 18-250 (love this lens) and use the combined funds to get an 18-55 or 18-70mm kit lens and used 80-200 f/2.8 (both Nikon). Option 3: ?