Would have to be the 1D MK3.
I'd go for a 1d3 but then again I already have one
I think you'd be happy with either body, I went for the 1d3 purely for the build quality. The 7D is a fantastic body but the 1d3 with it's better weather sealing and more rugged build was my choice.
Mine cost me over the odds as a factory refurb but with only 9380 shots on it when I got it and in absolute mint condition I was happy to pay a little extra.
Increased fps, better build and waterproof. All ideal for sports.
Thanks Barry
Is the MK4 a massive improvement on ther MK3?
Is it a significant upgrade to the 40D?
depends what your doing... I upgraded two mkIIIs to 2 mkIVs and cost me a fortune.. but the extra ISO and the few more MP made it truly worthwhile.. people say its not about the MP .. well yes it is when your using primes and esp for sports when you cant alway fill the frame.. the extra MP means you can crop moreThe ISO is far better than the MKIII by a million miles.. thats important for myself.. is it for you?
You would likely not be disappointed with either, but I can tell you, for free, that once you use a 1 series body, using anything else will just feel wrong. On that basis, you are best off getting a 7D. Forbidden fruit.....
PS, why not get a 1D mk 2? Sub-500 quid, and a stonking camera. There is no difference in image quality between this and the mk 3. The key differences are that the mk3 has a nicer screen (which is still some way behind the 7d), and has a clunky menu system. You will get used to it quickly, and can then enjoy spending £800 on new glass.