I've shot with both Nikons and Canons. They remain the two big forces in professional cameras. I've been adamantly trying to explain, however, to those who won't take them seriously, that Sony is starting to make better cameras than the big two.
Of course, respect comes slowly to any brand, and grudgingly. Now Pop Photo has a review of the new Sony Alpha 900 that hints at this. I say hints, because they explain the Sony beats cameras $5000 more expensive in major areas such as resolution, viewfinder and in-body image stablization -- the essentials of traditional photography -- but they nitpick with less-crucial areas such as live view and the ability to shoot HD video, which are sometimes useful but not the main point of a pro camera.
"With its first full-frame DSLR, Sony has shown that it can definitely run with the big boys. While we have yet to test Canon's new, midrange, full-frame 5D Mark II, this Sony currently packs the most resolution you can get in a DSLR. Add to that fast AF, an outrageously appealing viewfinder, and a body with a great grip and plenty of dedicated controls, and you've got a winner."