I disagree with lots of things said about mirrorless – and not just because I use one. Image quality is very good – I would say pretty much equal to an APSC DSLR in every day use. The body is smaller (certainly in the system I use), and most functions you use all the time are on dials/buttons – which are all fully customisable. It isn’t too small and cramped in use either, and believe me… my hands are almost certainly bigger than yours 😉
I use an Olympus OM-D EM5 most days with a nice selection of prime lenses (also much smaller than DSLR). Alamy and Getty are more than happy with the quality of the output and pictures from this system have been double page spreads in Outdoor Photography.
My other system is a full frame Nikon D800E so I do know what the other end of the spectrum looks and feels like!!!!
I would say go with whichever system suits you best. The best camera is, afterall, the one that you have with you – and personally I don’t think there is a bad camera or system out there these days.