The 1DX and 5Dmk3 essentially share the same AF system (and I believe the 7D2 is largely similar too), so in those terms there's little between them. The 1DX is much, much quicker in terms of frames per second though which may help. What lens are you using? That's likely to have a more significant impact on your hit rate than the differences between the cameras you mention.
I believe it was said very openly back in the day that 1DX had some extra tweaks.
1dx has the best AF of the three and the best high ISO.
Are you getting close to filling the frame or already doing significant crops on the 7d2? That might make a difference.
Oh, and is there any way you could afford the R6? That would be the best AF and best IQ of the 3 as long as you don't do huge crops.
Mike
Digic 5+ processor
Congrats on the new camera! It's far far better than the AF on the other bodies, and whilst not up to the standards of the latest mirrorless beasts you should notice a significant improvement in AF once you get it set up properly and give it a fair trial.
The files are a huge improvement of the 7d2, and as such that will negate a lot of the 'crop factor' as you can crop further into a high quality sharp file that you will get from the 1dx if you get it right.
Have fun!
Mike
I have bought one in good condition but with a shutter count of 82k which is higher than I would like but the price was very good and it should go on for years.
I will test it at the weekend and decide if it is worth keeping. The AF set up is very similar to the 7Dii and the 5Diii, whether it is better time will tell.
Couldn’t agree more, battery life is superb 1755 shots of half a charge says it all reallyI've had a 1DX for 3 years now, my keeper rate shot up to over 70% immediately!
Such a great camera, had many Canon DSLR's before like 5D3, 7D, 1DIV/III but nothing comes close to it!
I'll mention another thing...battery life! one charge on an LPE4N must be equal to about 5 charges of an LPE6N! and they just go on forever!
Congrats on the new camera! It's far far better than the AF on the other bodies, and whilst not up to the standards of the latest mirrorless beasts you should notice a significant improvement in AF once you get it set up properly and give it a fair trial.