I was switching from iPhone 4. Was familiar with Android from others' phones and my ASUS TF300 tablet.
At this point, it's about HTC One vs Samsung S4 in the Android market IMO. I'll show you the comparisons I made, HTC vs Samsung (respectively)
At base model, $200 vs $250
At base model, 32 GB (not expandable) storage vs 16 GB (expandable)
Non-removable vs removable battery
4 UltraPixels vs 13 MegaPixels
S4 has slightly larger screen, can't remember offhand the sizes.
Sense 5.0 vs TouchWiz
Aluminum body/attractive look vs. plastic/unexceptional look
Traditionally slower updates on HTC's end
BoomSound vs not BoomSound
I loved the look of the phone. It seems silly and for some people, it is. However, I'm going to live with this thing...it is basically going to be an extension of myself for years. Beyond that, it has to be more durable.
As far as Sense goes, I don't think it is an especially intrusive take on Android compared to TouchWiz. The BlinkFeed feature is something I decided I would use and have used, though I quickly made it a non-default home screen.
I didn't know that Beats audio would be so good, but it is -- it essentially gives you a perfect EQ whereas other phones skimp on this to save on battery. BoomSound is cool as well, I have it play music when I'm in the shower now and I can even hear it over the shower/vent.
I have expandable storage on my ASUS tablet and never got around to using it or felt like I needed it, so I knew it wasn't a feature I cared that much about on my phone especially when it comes with so much storage. The battery isn't amazing, but more or less the same as my iPhone. I will occasionally set it on power save mode throughout the day and in that case, the battery is exceptional.
For the camera, I looked at picture comparisons on CNET, etc. and saw that the HTC almost always looked better. It does better in indoor lighting, for sure, and that's what I need. Zoe is really cool as well. I would like the 4.2.2 update and I will probably get annoyed at the slow updates, but it isn't a big deal for now.