Here's my little review between both phones, my previous HTC One M8 ( converted to GPE ) I had for six months, and my new OnePlus One, I have had for one week now. I have lost track of all the different Android phones I have owned the past 5 years, but let me try to recap; MyTouch 3G...Nexus-One...EVO 4G...Nexus-S...EVO 3D...Galaxy S2...Galaxy Nexus...Galaxy S3...HTC One X...Note 2...Nexus 4...Galaxy S4...HTC One M8 GPE...OnePlus One. HTC One M8 ( GPE ) ; - Beautiful design, and excellent build quality, IMO best built / looking Android to date - Gorgeous screen - Very smooth and fast performer - Stock GPE / Nexus type OS is awesome on this phone - Battery life is very good for this size phone ( Averaged approx 5h Screen On time ) - Easily one handed phone - Speakers are amazing sounding, loud and crisp, and the sound faces you, not below or behind you OnePlus One; - Nice build quality, not as good as the One M8, but still pretty good - The screen might be better than the One M8, the whites are very white, and the brightness is super bright, I can keep it at 25% in the house and it's more than enough. - Performance is great, maybe a tad smoother than the One M8, but not by much - CM11S is very close in look and feel to a Nexus / GPE OS, just more customization - Battery life = AMAZING, I get easily 7h Screen On time, sometimes 8h Screen time - It's big, this 5.5" phone is hard to one hand comfortably - Speakers are very loud, and face downwards, which is noticeably different than the front facing speakers on the One M8 I gave my One M8 to my Wife, and setup it with CM11 and a Lollipop theme, so both phones look and run very similar. Funny thing is, when I play with her One M8 now, I feel a little sad I got rid of it, the size of the One M8 is damn near perfect, it's not tiny, and not huge, it feels very comfortable one handed. The OnePlus One, to me, is on that border of being just too large, so there's no way I would like the Nexus 6, that would be just too large for me to ever be comfortable with. Funny, I got rid of Note 2 back in the day, due to it's large size, just couldn't text one handed easily on it, or reach the top corners of the screen without always shuffling the phone in my hand, but the One M8 could all be done with one hand only. But the battery life and and very bright screen of the OnePlus One is a huge plus. For work this OnePlus One never dies on me, I hammer my phone all day long for business, and most phones die by the afternoon, or the One M8 would be in the red % by end of the work day or dinner time, but the OnePlus One still has plenty of juice even at midnight. Overall I really like the OnePlus One, only drawback being the size, I feel the One M8 is more of a comfortable phone to use. I have a case on my OnePlus One, the Diztronic slim case, but without a case on, the OnePlus is even more AWESOME feels lighter and easier to use obviously, but then I'm afraid of dropping and breaking the phone. Once the official Android 5.0 Lollipop build comes to GPE for the One M8, we'll see what I do, I may ask my wife for the phone back and give her the OnePlus One, or trade it online for another One M8. But the battery life on the OnePlus is a HUGE deal to me. I have checked out all the other popular phones out there in the stores, like the Galaxy S5 ( Don't like Touchwiz, and hate the hardware buttons ), LG G3 ( Laggy, and underpowered for that 1440p IMO ), iPhone 6 Plus ( Not an iOS fan ), Note 4 ( Very nice, but too large and Touchwiz not my cup of tea ) etc...to me, I still think the One M8 and OnePlus One, are the best of the best for Android. For a smaller phone the One M8 is the king for 2014, and for a battery champion and larg screen the OnePlus One wins.