@omersak I see from your signator, you use of Galaxy S5 + Xperia Z2 + One M8 .
Which one of these phones have better daily use?
My poins is:
Best battery life
Goooooood performance and smooth UI
Goooooood camera quality
Best battery life: Z2 > M8 > GS5
Performance: M8 > Z2 > GS5
Camera: Z2 = GS5 (GS5 is better in daylight and Z2 better in indoors and low light) > M8
I first got a GS5 and I quite loved it for its camera, features and erognomics but it was horrible at maintaining a stable LTE signal at my office and that would drain the battery pronto. Other annoyances about it was the comparatively laggy and slow UI, especially coming from a nexus 5, and it's low-light blurry camera shots (these issues may or may not have been fixed via firmware upgrade). Had it for around 10 days.
I then got an M8 and really loved it for it's build quality, speakers and fast UI - faster than the nexus 5 even. It held the LTE signal well and had good battery life, lasting me a full day. Unfortunately it's camera was beyond awful and beyond my patience and was thus unacceptable for me. Also, like the M7 before it, the M8's UI was too sterile and boring for my tastes. Had it for around two weeks and got bored.
For me, the Z2 has been the best overall package of the three with that huge battery, potentially great camera and good performance. I've had it for 2 months now it has the best of both the GS5 and M8, along with the best battery of the bunch. The camera is capable of producing phenomenal results in any lighting conditions, the battery can easily last me two days and beyond, the UI is quick and pleasant to use, the screen is bigger and nicer than the other two (IMO) and I love the build quality and water-resistant features. The speakers also fall in between the M8 and GS5, and are good.
It's not as easy in the hand as the other two though, but if you can get to hold it for yourself and find it acceptable, this really is the best all-round phone in the market IMO.