Originally posted by jawats I have the 150-450mm, which I love. However, for basketball and portraits, it's a bit long. Thank you!
Just stumbled on this thread so I'm probably late to offer advice.
I also have both the Tamron and Sigma 70-200's, as well as both the 1.4 and 2x matched Sigma TC's. The image quality between the two is so close that I'd say you would not normally be able to tell which is which from a photo render. I prefer the handling of the Tamron, it's a bit lighter I think, and the finish is definitely nicer than the matte Sigma. But I have matched TC's for the Sigma which is why I keep it around. I had the 1.4 Tamron TC too but sold it since my Pentax HD TC works as well or better with it. If you already have one or the other 70-200 I don't think it would benefit you to sell it for it's cousin.
But I also have the Pentax DFA 70-200 which performs better than either of the third party lenses, and is by far my preferred lens for "people" stuff. It's what goes with me for outdoor model/portrait shoots. It's faster to focus and with more certainty, and better overall image quality for sure. So why keep the other two at all, right?
Well, that Pentax is a heavy beast, and if the use isn't critical, or it's a long event, I'd much sooner carry either the Tamron or Sigma. I did the Pentax for 6 hours (7??) essentially non-stop as a paid photog for a regional music fest and my arm
loudly complained for the following two days. For that one, and what they did with the photos afterwards (90%+ social sharing), either third party lens would have been fine. I overthought it.