Yeah I fall in the same boat. I'm rooting for HTC because they made the first android phone that I thought was 'done right' - the One M7. Beautiful metal build, great design, great software. It did everything really well and didn't cheap out on anything. Sure the camera wasn't spectacular, but 4mp for shots people share on social media is fine.
The M8 came out with a smoother design, super slick software etc and I loved that phone as well. M9 was a bit of a misstep, but from what I hear, people who owned the M9 enjoyed it.
Since the M8, I've had Xperia Z2, Z3, Galaxy S6, LG G4 and now currently on the Nexus 6P. I've liked the 6P is the best of those phones, but I'm still looking forward to the HTC 10. For whatever reason I just enjoy using their phones the most. Not sure if it's the software or the hardware or what.
The S7 and G5 aren't even on my radar. Weren't really happy with their predecessors last year. While I'm sure they're great phones in their own right, they just lack something that I found HTC phones to have. Can't put my finger on it, but I think just the speed/fluidity of the UI, pared with the great hardware just made HTC phones a seamless experience. Didn't feel like had to screw around with settings or apps or put up with bouts of lag etc.
This could very well be the best phone of the year, and unfortunately, it could very well be HTC's last flagship phone. I certainly hope not, but new financial reports coming out don't sound promising for HTC.