5d iii because you mentioned sports events
Yeah, I agree.
I have shot some sporting events with the 5d2 and frankly, it sucks. Slow FPS, crappy focus with only one cross type focus point.
I am NOT in love with my 5d2. Anything low light or moving? I hate it. I default to my 7D more often than my 5d2.
I'd actually say your choices would be either the 5d3 or the 7D according to what you want to shoot.
My thoughts: If you start with the 7D now you can shoot everything you want to shoot with it. You WILL need a second body as a back up down the line when working professionally. The price will eventually drop down a bit on the 5d3. Give it a year. Then pick that up as your primary and the 7D as your secondary.
Your most important investment will be your lenses. I won't tell you what lenses YOU need because it all depends on the style of the shooter.
I can tell you what I would do: As a sports shooter I cannot live without my 70-200 f/2.8 OS, Sigma. I also use it for most portraits and for weddings.
I am a zoom kind of shooter, so my next necessary lens would be the 24-70 f/2.8L or a similar lens like the Sigma 24-70 f/2.8 or the Tamron 24-70 f/2.8.
For portraits I LOVE my 28mm. I would shoot with all primes for portraiture if I had them. I have a 50mm and I am desperately wanting the 50 f/1.4 and the 85 f/1.4 for portraits. They'll be on this year's list for upgrades. Primes are the sharpest of sharp lenses. L glass primes are beyond my upgrade budget at this point, but they are the best of the best glass.
What you choose to shoot with is almost as personal as what kind of underwear you wear. It has to fit YOU and YOUR needs, style and comfort zone.