[AT&T HTC One (M8)] bilibug:
I too was in a position to choose between the M8 and S5 when my Galaxy Note II decided to finally give up the ghost only after 18 months of use. Despite a full restore it just kept freezing up and corrupted not only my 64 GB SD card, but also the internal memory. Because my phone is my lifeline, I couldn't afford to take any more time to try to fix it, and bought a replacement - the M8.

I have never had as many issues or physically destroyed a phone as quickly as the Note II. While I enjoyed the plastic at the beginning due to making the weight of the phone lighter, it was also more prone to scratches, cracks, abrasion marks, etc. Although I liked the Touchwiz features, I hated the FischerPrice design. Why are all of the icons huge on the screen? Nova launcher quickly became my friend.

I temporarily reverted to my Iphone 4 while shopping for a new phone. While I also hate IOS7, i did realize that I missed the feel and sturdiness of the metal chassis design. This swayed me to look at the M8 after I found out that the new model was almost all metal, unlike the M7.

I viewed the reviews and specs of both the M8 and S5. While the better camera on the S5 was definitely important, these were the factors that made me choose the M8:

1) Metal iPhone like build. I'm not too rough on my phones, but the even more plastic flimsy build of the S5 didn't seem like it would hold up any better than my Note 2 did. i also hated the new Band-Aid like design. The S5 looks like a toy.

2) Dual stereo speakers. I am a musician and DJ. Music is my life. While the volume of the Note 2 and S5 were "ok', there is no doubt that the M8 was not only superior in sound quality, but offered the rare stereo experience.

3) Camera - the M8 is adequate, but not up to par with other phones, especially the S5 and new LG. However, I weighed this against my use of the device for music. I rarely take photos or videos with my phone. Yeah, every once in a while as a spur of the moment keepsake, or to send to someone, but never to save and print, etc. I realized that the camera was the least important feature to me, so even though the S5 would win in this category, the M8 was sufficient for my needs. That being said, some of the camera features are very nice, and if you use manual mode, you can get some pretty decent shots.

4) Size - Although I liked the bigger screen on the S5, and prefer the technology, I found my Note 2 to be just a tad too big every once in a while. The slightly smaller M8 seemed to still give me the larger real estate that I wanted (compared to the minuscule iPhone 4, which I found unusable for non mobile web browsing). I was not mistaken.

5) Interface. I was very surprised with how clean the Sense 6 interface was. Although I don't use BlinkFeed (not customizable enough for me) it seems like so much more a native android experience. I don't feel like it gets in the way like TW did. I don't even use Nova anymore, simply because I love the weather clock widget. It was designed with simplicity in mind, but not to a point of making it toy like. If anything, it is elegant.

6) Internal memory. The S5 only has 16 GB of internal memory. The M8 has 32. Let's face it, there's a lot that can not be stored on an external SD card.

Other factors -

I really like the dot view case. While I thought it was gimmicky at first, I really find it helpful. The scrolling caller ID, the tap to view time/weather, the quick voice call feature, auto on/off when opening/closing the cover. Actually all very useful.

I do miss having a full RGB led notification indicator. However I'm finding it less important than I did on the Note 2.

I actually like the stock music player. I used Google Play Music on the Note, but now only use it for cloud based stuff (21K songs LOL). Otherwise I've been using the native player. I like the Music Channel feature with the scrolling lyrics.

One thing that almost made me overlook the M8 was that the M7 did not have a removable battery or SD slot. The M8 now features a micro SD slot (up to 128 GB!) so that's no longer an issue. While the M8 still does not have a removable battery, I find the battery life of the phone to be amazing. I do tend to have it on a charger most days, but yesterday I spent 14 hours at the casino. Even with constantly checking my phone, using it for several calls, texts, etc., I still had 20% at the end of the day without using power saver mode. My note would have been dead in 6-8 hours.

Even with the announcement of the New iPhone 6, I do not regret my choice of the M8. I really enjoy using this phone. YMMV, but the best thing to do would be to evaluate the features and how they fit your needs.