Okay, I've got to defend Canon on this, once again! Much of the talk about dynamic range is a myth.
Yes, the sensors that Nikon buys from Sony... and that they both use in their cameras... typically offer between 2/3 and 1 stop wider dynamic range than the most comparable Canon sensors, all of which Canon makes themselves exclusively for use in their own cameras...
but primarily or near at the respective cameras' base ISO.
At higher ISO settings, Canon actually match or offer slightly wider dynamic range the most comparable Sony/Nikon .
For example, at ISO 100...
Nikon D850 (46MP, intro'd Sept. 2017) has about 11.4 stops DR.
Nikon D810 (36MP, July 2014).......................... 11.2 stops DR.
Canon 5D Mark IV (30MP, August 2016)............. 10.6 stops DR.
Canon 5DS-R (50MP, June 2015)........................ 9.5 stops DR.
Now increase the cameras to ISO 800...
Nikon D850...................................................... 8.9 stops DR
Canon 5D Mark IV............................................. 8.9 stops DR
Nikon D810...................................................... 8.4 stops DR
Canon 5DS-R.................................................... 8.3 stops DR
And then increase the cameras to ISO 3200...
Canon 5D Mark IV............................................. 7.1 stops DR
Nikon D850...................................................... 7.0 stops DR
Canon 5DS-R.................................................... 6.7 stops DR
Nikon D810...................................................... 6.7 stops DR
Or even higher to ISO 12800...
Canon 5D Mark IV............................................. 5.2 stops DR
Nikon D850...................................................... 5.0 stops DR
Canon 5DS-R (max expansion setting)................. 4.8 stops DR
Nikon D810...................................................... 4.7 stops DR
There are lots of other things to consider, besides DR. For example, the Canon 5DS-R has the highest resolution of them all, but also has the most limited ISO range (100 to 6400, expandable to 50 and 12800). And, the D850's actual base ISO is 64... not 100 as used for the above comparison. The newest of the full frame models listed, among them it also has the widest range of ISOs (64 to 25600, expandable to 32, 50, 51200 and 102400). There are many other factors that need to be compared... frame rate, autofocus system, price, availability and cost of lenses and other accessories, etc., etc.
You can compare Nikon D610 and D750 (both 24MP, FX) with Canon 6D (20MP FF) and 6D Mark II (26MP FF).
Yes, full frame typically offer wider DR than crop sensor cameras. As much as one or two stops, in some cases. But, as you say, that's "manageable" with various techniques. Especially since ALL these cameras, both FF and crop, now use CMOS sensors. In terms of DR and high ISO noise handling, CMOS are light years ahead of the CCD sensors that some manufacturers continued to use for too long!
Putting aside the superior DR of full frame, if you compare DR of Canon APS-C with DR of Nikon/Sony APS-C, you'll again find that the latter typically offer slightly more at their base ISO, but the difference disappears at higher ISO and that the most comparable Canon tend to offer the same or slightly wider DR at higher ISO, much like is seen above comparing the full frame models. But you'll also have to consider the age or "generation" of the sensors being compared. For example, the Nikon D500 uses a much newer 21MP sensor than the Canon 7D Mark II. The D500 (April 2016) is only about a year and a half newer model, but it got a brand new sensor. In comparison, the 7DII (Sept. 2014) was basically fitted with the same 20MP sensor as was introduced in the Canon 70D (Aug. 2013).
Look for yourself:
http://www.photonstophotos.net/Charts/PDR.htmCanon and Nikon tend to leap-frog each other with their new model introductions.... At this point in time, among the above models the Nikon D850 is the "latest and greatest". But Canon will probably be the next to upgrade and will likely roll out a product that out-does the D850 in some ways. Likewise, we'll probably see an update to the D750/D610 some time before Canon updates their 6D Mark II.... And there's likely to be a new 7D Mark III some time before the D500 gets updated (keep in mind that there was an 8-1/2 year "eternity" between the introduction of the D300 and that of the D500, with only a mildly updated D300e in between). What the specs of next generation models will be... we'll just have to wait and see. Heck, maybe they'll be mirrorless!
Okay, I've got to defend Canon on this, once again... (