I have 5d Mark III, Tamron 28-75 2.8, and few primes 40 2.8, 50 1.4, 85 1.8, 135 2.0, and finally 17-40 that I got recently (used) and seem to rarely use. I'm mostly taking pictures indoors, fast moving twins, trying mostly without flash, as I can't bounce effectively when subject is very close (jumping on me).
I use 28-75 quite a bit, always on 2.8, unless one of the primes is on (love shallow depth of field). I find that I often want just a bit more than 75mm to not change position and capture moment.
So I find myself constantly drawn to 24-105, though I rented it when I had 5D mark II, and I wasn't crazy about it, 4.0 felt slow inside of my house. But, I feel like it would be such practical lens because of range, set and forget, that I'm thinking of selling 17-40 and buying 24-105. But then, I can spend few more bucks and get Tamron 24-70 2.8. Currently, in Toronto, it would be less than 50% to jump from craigslist 24-105 to retail Tamron 24-70 2.8.
Am I just going crazy because I want to spend some money? Or is there real benefit to getting one of these 2...