I have a Note 3 and HTC One M8, work in a phone shop too The M8 is by far my favourite over my Note 3, so quick and does everything instantly, the full metal body feels so good to hold too and looks incredible.

S5 is powerful and amazing also however comparing the two phones at work on a daily basis the M8 comes out on top in most instances.

However at the end of the day when they are that close in comparison, it really does come down to Personal Preference and what you prefer. Guess i've always liked HTC since I had they're One M7 I fell in love with it so the M8 was a certain buy for myself.