I bought a system from B&H a few years back. 2 HIk cameras and a HIK NVR. The only real advantage to me, was that you could actually talk to Hikvision.
I have not had to deal with warranty service on either NVR or my cameras.
Hikvision support was helpful via email exchanges in a software issue I had getting the software running to remote view.
I recently purchased 2 systems from Nelly's. He was
extremely helpful in setting my "unbranded" NVR up. The first system has been running for months now at my office. I am about to call them again to setup the second system I bought. I'd say they were superior in their service.
BTW at the time, I paid more at B&H for the same cameras I could have purchased Grey Market, even after not paying tax, when B&H didnt charge tax NY to CA. I got a taste of guff here from people at the time telling me I was wasting money buying from B&H.
They were probably right.