I have had several experiences with Bushnell, dealing in person with the Markham warranty facility. All were outstanding, in most cases the obsolete, many-years-old scopes I brought in were replaced on the spot with new and higher-grade optics. I have heard that dealing with them by mail can be very slow.
One experience with Swarovski warranty service and it was very poor. The binocular was rebuilt cosmetically, and an upgrade was performed on the diopter adjustment...but the complaint for which I originally brought it in was completely ignored. It took them the better part of a year for that "service". I don't know if they sent it to Austria, or maybe off-planet, but I was not happy.
Zeiss took very good care of me the single time I needed them. Binocular again, and close to ten years old, came back like new within a couple of months. Nice.
Leupold has been quick and trouble-free for me several times on riflescopes. Problem always corrected, turn-around time never more than a couple of weeks.
Nikon will never see another dollar of mine. Dealt in person with the Mississauga depot. Very rude and abrupt service rep. Warranty denied, and the best (?) part was that she quoted me a price for the repair before even asking what the problem was! The cost was very nearly enough to just throw the binocular away (not their high-grade product), but I decided to pay it. The work was done properly, but I'm done with them.