One more remark that keeps cropping up no matter where you read such, is that in trying to do everything, it succeeds, but, in each segment of that everything, a specialized, dedicated, "L" quality lens produces better images. OK. That is accepted. It is just the Tamron or the Sigma takes the place of, but doesn't replace, three to five high quality lenses. Most serious photographers, taking pictures for pay, art, or bragging rights, would not use them. They'd use primes, or "L" glass, or Zeiss.
Maybe later, when I can save more money, I'll get serious glass. Start with a 10-24?