I personally own Canon, Nikon and Sony systems, and I like/love parts of each of these systems enough to keep them all.
(The Nikon system consists of the D70, D7100 and D7200 bodies. The Sony system is mirrorless with the Nex 5n and a6000. The Canon system is my primary shooting system with more bodies than I care to admit, but I use the 5D Mark III and 7D [original] the most.)
Comparing recent Canon sensors' Dynamic Range (DR) (specifically the 1Dx Mark II, 5D Mark IV and 7D Mark II) with the latest Sony sensors, the Canon sensors tend to hold their own and sometimes beat the Sony sensors by ISO 400 and beyond. The only region where Sony sensors reign supreme (and, by proxy, Nikon and Pentax cameras with Sony sensors) is at base ISO, where the extra DR is often underutilized by the majority of shooters. (The extra dynamic range is not automatically included in either in-camera JPGs or in default RAW rendering by major software manufacturers.)
I will admit that the extra Sony-imager DR does come in handy for indoor and low-light photography when the flash fails to fire (either by my mistake or by overrunning the flash recycle capability). However, that usually means either my failure or the equipment failure (recycle speed), so the post-processing recovery involved is a bit of a crutch.
The very latest Canon sensors will recover at least 3-stops of shadow in post-processing, with FF sensors (specifically the 1Dx Mark II and Canon 5D Mark IV) able to recover up to 4.5 stops, in a perfect situation. This makes these Canon cameras nearly up to Sony sensor standards.
The area where Canon still reigns is in autofocus (AF) and Canon AF is unbeatable in reduced light, indoors or outdoors, and especially excellent using a high-end flash with AF Assist.
I am now retired but my last working wedding I used a Canon 5D Mark II for the formals and a Canon 7D [original] and did not lose a single formal image to missed focus, the result of careful setup and execution, and only 6 candids were OOF, out of 1600 total, using the 7D with a Canon EF-S 17-55mm, f2.8 IS USM and a Canon EF 70-200mm, f2.8L USM (version 1). In the case of the candids I credit the success to the Canon 580EX (original) flash with an external high-voltage power supply to assist recycle speeds. (The 6 AF failures using the 7D were my inability to follow/guess the action properly.)
Since absolutely nothing spoils a shot worse than missed focus, the Canon system is my vastly preferred system, and recommendation, for events and for any sort of action photography, including sports, wildlife, BIF, children, etc.
To understand why the very latest Canon AF systems are so uniquely qualified and competent, read this article by Roger Cicala of Lens Rentals,