Well unless your capturing very, very fast action a lot 10 FPS vrs 6 FPS probably won't be as big a deal as you might think. It might get you a shot or two that you may have missed otherwise. If you were doing a ton of photography where you were trying to capture high speed action this might be worth looking at, but really for most folks 6 FPS is more than adequate. I do some wildlife photography and honestly I've never needed more than that. As for megapixels, really the difference there will usually only matter if your doing a lot of cropping on your images, so if you don't need to crop so much you probably won't see a huge difference between 20 and 24 mp.
The 7d Mark II does have some advantages, but it is about $1400 wheras most 7200's run for less than $1000. If you are going to go that route I'd probably look at a used or refurbished Nikon D610 or D800 - both of which can be had for about what you'd pay for a 7d Mark II - and both of those are full frame cameras which will give you much better lowlight abilities.
So really if you want my opinion Canon/Nikon isn't really going to matter that much, what will make the biggest difference in the end results is learning how to use whatever equipment you ultimately buy. The end results will be based more on your skills rather than the equipment. Sure, better equipment makes some things easier, but when it's all said and done the linkage between the camera and the ground is the most important factor.