Mirrorless or DSLR, for strictly photos

Sony NEX 6

Canon t3i. Mine is miles better than my moms canon xti. and it takes wicked video for a good price

Most mirrorless cameras these days will be able to match the xt's 3fps.

do you have a budget, and what style of shooting?
mirrorless tend to have better video, though some canons can shoot raw
mirrorless cameras are becoming more popular for street photography because of their small size
the on-d has continuous live view during bulb, which is amazing if you shoot stars, because you can keep it open and watch the picture get created as it is being taken, and then stop the exposure when you like what you see

dslrs hands down have better autofocus. Much more accurate for sports. This doesn't really matter for wide-angle shots because the dof is so deep, but for longer lenses it is huge. MIrrorless cameras sometimes have usable AF for video, and it works great for stills, very accurate and lenses/bodies never need micro-adjsutments, but it is a little bit slower. Both systems are working towards solutions, canon added stm and on sensor focusing to use during video, like mirrorless, and I think a few companies are working on adding on sensor phase detect af for mirror less bodies.

for size, mirrorless cameras are typically smaller, some are pocketable with the right lens. They are also usually lighter, if this matters to you, but most of the weight will come from your lenses/accessories.

lenses are one of the most important parts, and as far as native lenses, canon wins. They have a great range of their own and third party lenses covering every focal length and price range. This is getting better for mirrorless systems, and while many of them are great lenses, there aren't many cheap native ones. Canon has decent compatibility with old lenses, but mirrorless systems win this one hands down, as they can take nearly any lens ever made.

flash control is the last one coming to mind, and I have to run, so let me know if I forgot anything major. Typically canon is better, there are more flashes/better compatibility, and there is just more information out there about it especially for sports related applications.

Thanks so much for your advice, probably >$500 and most of the time i am within 30ft of the rider or object using manual focus and sports mode with my 18-55mm stock lense.

fuji x100s?

I assume you mean less than $500, and if you only want stills, look at a 40d, 50d, or 1d mark ii (n) (I use the "n" version for stills). Your 18-55 will work on the 40d or 50d, not on the 1d, but Either way I would suggest you get a new lens. You can get an older tamron zoom, its f2.8, 28mm on the wide end (so not super wide on a crop), and its either 70, 75, or 80mm on the long end. They all exist, but one is much better, and I think sub $300 used. I don't think it has super fast AF like canon USM/"L" lenses, but it should work for most of your stuff. I'm not sure if the better AF of the 1d will help, or if it would be a waste and the lens is the same on all 3, maybe someone else will know. After that, 70-200 or 11-16/fisheye if you want.

If you have trouble deciding between the three, here is a little breakdown.

40D - 10MP, 6.5 FPS, Cheapest
50D - 15MP, 6 FPS, still cheap but newer version of 40D, does video with magic lantern
1D Mark II - 8MP, APS-H (instead of APS-C like the other two), 8.5 FPS, built like a tank, too many AF points to count, the n version has the biggest screen, and I think it is the most expensive of the three

Thank you so much +K

A t3i without the video feature is pretty much how I would describe the Canon t3, But for stills the options p.hawks gave you are better for sure.

no problem man, feel free to pm or post if you need help finding the lens or have questions about the 1d. I don't know as much about the other stuff haha