It's all about personal preference.

Personally I can't stand Samsung phones. The glossy all glass build makes them a fingerprint magnet and an accident waiting to happen. It doesn't seem like they could survive even the slightest fall. And touchwiz and the overly saturated screens aren't my thing either. I much prefer the feel and build quality of HTC phones. But that's just me. Obviously I'm i the minority because Sammy sells lots more phones than HTC. Best thing to do is get some hands on time with both phones and see which one you like better. I was ready to pull the trigger on an S6 last year until I went to Best Buy and played with it for a while. Ended up going with M8 instead.
I think the S7 is just about the best looking phone out there (partially because I had an M7, so the 10's design isn't quite as exciting to me), but I'll definitely agree about the fingerprint thing; I just gave up caring after a couple days.
However, I've never understood the "this phone is more durable" argument; if durability is what one looks for, shouldn't we all be going towards the Samsung Active series, Droid Turbo whatever, etc.? If you drop your HTC 10, the thing's going to get a really ugly dent in it (I know, because I got one on my M7). I guess from the perspective of feeling the need to send the device in for service, sure, it's a step up from a potential crack in the S7's glass, but both phones are going to get messed up by a drop, so you're best off with a case either way.
I agree that TouchWiz sucks (okay, not really anymore, but I'd still rather have Sense), but I also think the S7 on "basic" display mode is pretty decent in the saturation dept. I'll have to do a side-by-side with my M7 to be sure, but it seems pretty decent (although, why get an AMOLED display if you're turning the saturation all the way down, right?).
Either way, I think the reason Samsung sells is because their marketing dept. is ON IT. They've come up with some amusing ads (come on, the Lil Wayne TV spots are pretty funny), and their phones are all over
everything. And if you're tired of seeing the campaign, it's working; the average person will now walk into a phone store and say "hmm, might as well check out that new Samsung phone that they claim is awesome." Whereas they may just walk right by the HTC 10, since they won't know it exists (and it's easy to get overwhelmed by options in those stores).
Edit: Not trying to be argumentative, just giving my opinion; I like hearing people's perspectives on these phones.