do you really suspect that Nikon is going to be that much better to deal with? Maybe sigma or tamron because they can't afford to alienate their customer base, but I doubt they are giving away free service either.
having said all that, I have heard of times where someone sends in something for service to Canon and they do the work for free even though it is it of warranty. so they aren't all bad.
I have no idea whether Nikon is better, worse, the same, whatever. But for me anyway, continuing to do business with Canon USA is not going to happen due to two poor experiences - one my own and another a family member.
In my case an L lens only 3 months out of warranty (which they adamantly stated would not be covered) so for me, I can rule out that Canon USA covers expensive items just recently going out of warranty. Which is fair enough, I agreed to pay for repairs, the problem is repairs to fix the actual problem were not performed and Canon USA was not helpful to resolve the issue, yet still has my repair payment.
In mother in law's case, I can rule out that Canon USA covers items that are in warranty, and fails to provide any explanation that is meaningful as to why they refuse to perform their obligation.
So that's my experiences and why I won't do business with them anymore. Others may have direct first hand experiences that are better.
And again, the pragmatic lesson is just buy gray market or non-authorized reseller if you want to shoot Canon and don't waste money on warranties, either first party or third party. And as for me, I'll just rotate this gear out when the time is right and migrate to another vendor.