I just want to share my excitement, i bought a 5D Mk III today, ordered online actually so i will arrive next week but man am i excited, been rocking a 60D for a year and a half and it has been a great companion but i've been meaning to go FF for a while and the time is finally here for me. Got a great deal for the kit here in Mexico and i went for it. I'll be using it mainly for weddings and sports events(local baseball team)
Now to decide which lens to get, i have an awesome 17-55 2.8 on my 60D as well as the cheap but awesome 50mm 1.8. I've tried the 24-105 before on my 60D and i'm not crazy about it so i was thinking of selling it and getting something else, what would you guys recommend considering i'll be using the 60D + 17-55 for group shots and the 5d for the more artistic shots.
I have had the same 60D + 5D Mark III combo for over a year already.
Since you have the 17-55 range covered already, I would go with a fast prime setup on the 5D.
Especially since from what I have seen of your work, which is portraiture.
A Sigma 35mm f/1.4 DG USM + Canon EF 135mm f/2.0L USM combination would be ideal.
I tried the new Sigma 35mm f/1.4 on my camera yesterday, and it does live up to the hype.
Very sharp wide open. It would be my ideal street photography lens.
You can swap out the 135L with one of these, if you find that lens too long or limiting:
Sigma 85mm f/1.4 EX DG HSM
Canon EF 85mm f/1.2L USM (slow for sports, excellent for portraits)
Canon EF 85mm f/1.8 USM (fast AF, purple fringing @ f/1.8)
(These three become 135mm like lenses on the 60D.)
Canon EF 100mm f/2.0 USM
or
70-200mm f2.8L II IS USM (probably your best choice since you are covering a baseball team, yet still great for portraits.)
Eventually, I think you should sell the 17-55mm f/2.8 IS USM.
This lens still fetches most of what you have paid for it.
Replace it with either the 17-40L or 16-35L II. You can still have the 17-55 range covered on the 60D, and have a nice ultra wide lens for your 5D Mark III.
Or, use the money on the new 24-70L II.
I usually use my 5D Mark III from the ultra wide to medium telephoto range, and anything above that, on the 60D.