I've been an HTC user for 12 years or more now in one manner or another. It's not that I'm brand loyal, it's just what I was using, since the days of the HTC built HP iPAQ PDAs, to my Dell Axim x51v and my last WM phone a TP2 via Sprint and now my Arrive. It's just worked out that way. I can say I've never had any trouble with them except for my TP2 and I guess I had NIB unit go bad after a couple of years and followed up by bad refurbs before they gave me an Arrive in it's place. So far, 1 year later, no problems with it.
HTC makes good devices. So do the others. My wife has a Samsung Epic 4g slider that she'll only give up if you pry it from her hands and get it passed her sharpened finger nails. I can't speak personally for Nokia, but other than the typical first adopter issues with hardware/software, I've really heard no ill remarks towards them either. they seem to have gone a long way, working with MS, to put together phones that work well.