[Sprint HTC One (M8)] mswlogo:
I reformatted all the differences I see into a weighted Excel Spread Sheet.

Everyone will have their own weights.

So I attached the spread sheet for anyone to play with.

You can see why it's hard deciding between these two phones.

This is not putting down either phone. Just helping folks decide what's best for them. I own both phones.

Here is a crude view of the spread sheet.

Note: I have a Weight then a score for each phone, then I calculate a weighted value for each and then add it all up.

Feature Weight S5 S5 Weighted M8 M8 Weighted Comments
Camera 10 5 50 5 50 Equal but different until more testing
Speakers 6 6 36 10 60 No brainer but not critical in practice
Form Factor 10 7 70 6 60 M8 too heavy and tall
Staying Pristine 7 7 49 7 49 S5 Plastic Can Dent Scratch, M8 Speaker Grills Easily Clog
Serviceable 5 7 35 3 15 S5 Removable Back, User Replaceable Battery
Stock Browser 10 6 60 9 90 HTC Knows how to wrap text on double tap Zoom
Launcher 5 5 25 7 35 Slight Edge to M8 Sense 6 (this is just the launcher)
Setup/Quick Settings 7 4 28 8 56 M8/Sense allows both extensive and toggle in the same shortcut
Reliability 10 8 80 4 40 Too many failing M8's
Signal Strength/Stabil 10 7 70 7 70 Indistinguishable
Restore Stock 10 5 50 9 90 M8 with S-OFF can be made Factory or Look Factory
Boot loader Unlock 10 7 70 4 40 M8 requires signing release
Blink feed 5 4 20 8 40 S5 Magazine just doesn't compare with Blink feed
USB Mass Storage 10 3 30 10 100 USB 3.0 not very useful without Mass Storage Mode
USB 3.0 5 10 50 0 0
Water Resistant 7 10 70 4 28 M8 isn't exactly 0
Wireless Charging 5 8 40 0 0 S5 offers an alternate back
Headphone Jack Positio 4 8 32 5 20 M8 bottom, S5 Top
Fingerprint reader 2 10 20 0 0
Heart rate Monitor 0 10 0 0 0
Pedometer 2 10 20 0 0 M8 might be able to do this with 3rd party app, drain battery?
Charging LED 1 7 7 4 4 M8 Charging LED is too small
Microphone Quality 5 5 25 8 40 Not scientifically tested
Internal SD Capacity 3 5 15 8 24 M8 has 32GB internal SD, S5 has 16GB (Sprint) for same price
HTC Weather/Clock 3 5 15 8 24 M8 has more widgets, options and looks
Look & Feel Software 5 5 25 9 45 M8 has a very business look and feel through out vs S5
Vulnerability of Camer 5 5 25 7 35 M8 Camera is recessed, S5 protrudes
Screen Quality 10 10 100 10 100 Both fantastic screens
Nav Buttons 5 8 40 5 25 S5 Dedicated, M8 on screen but well implemented
Quality of Cable 3 5 15 7 21 Neither is great but S5 cable very stiff
LED Flash 4 5 20 8 32 M8 has dual color LED Flash (strong and helps white balance)
IR emitter 2 10 20 0 0 S5 Has IR Emitter and very flexible software to use it for controlling TV's
Software from manufact 5 7 35 7 35 I'm going to assume RUU availability etc. are equal for now
WIFI Hotspot with Root 10 10 100 10 100
S-OFF-able 0 5 0 10 0 M8 is usually S-OFF able which gives greater flexibility of Flashing Firmware (Dupe of Return to Stock)
Stock Keyboard 3 8 24 6 18 S5 has very nice keyboard, but many swear by M8's Swipe
Stock Malware 5 6 30 5 25 Slight edge to S5 for not hiding it as much as M8
Bluetooth 10 8 80 7 70 Slight edge to S5 for how it handles Voice Texting from Jeep Uconnect over M8 (even with S5 Nav sound g
Harmon Kardon enhancem 2 0 0 10 20 Slight edge to M8 for this being available.
Running Tasks Widget 2 8 16 5 10 There might be free widget that does the same, but it's nice S5 includes it from factory
Windows Drivers 3 8 24 7 21 Slight Edge to S5 for clean standalone drivers straight from them
Risk of Dropping 5 7 35 5 25 M8 heavy slick case more vulnerable to dropping vs textured S5
Handling Off Peak Emai 10 9 90 10 100 Slight Edge to M8 because of how awkward it is to get too and how stupidly they named things
Home Button 3 7 21 8 24 Slight Edge to M8 for a normal home button, S5 can slow you down with it's clickable button
USB Cover 5 8 40 4 20 Slight edge to S5 to have this to protect this vulnerable socket for more than just water but very flim
Gesture Wakeup 2 5 10 8 16 Might be doable on S5, I found M8 not reliable if you just turned it off it won't respond for few secon
Total 1717 1677
Equivalency 98% 102%

Pool Shot Original Size (M8) https://farm3.staticflickr.com/2923/14171498751_83390f8f4c_o_d.jpg

Pool Shot Original Size (S5) https://farm3.staticflickr.com/2898/14020429360_456b4315ae_o_d.jpg

Dog Bed Original Size (M8) https://farm8.staticflickr.com/7329/14174807495_4fa6c37e44_o_d.jpg

Dog bed Original size (S5) https://farm3.staticflickr.com/2903/14206967964_654fb8ed09_o_d.jpg

EDIT: I've updated and uploaded a V2 of my Spreadsheet have several months with S5. I have not had a chance to edit the table above. I am switching back to an M8.