I am currently having these 3 phones : Nexus 6P ( 3 GB ram/128gb), LG V10 ( 4GB ram/64 GB) and Mate 8 ( 4GB ram/64GB). My Nexus 6P was purchased from Techbug.my while both V10 and Mate 8 was from valuebasket.com
These 3 phones I had rated as the best 3 phablets I had used in the past one year. I had often being asked which of these are the best ?

Seriously there is NO best phone as each of these phones has its pros and cons
I'd say the more appropriate question is which of these phones I had a preference to use as my main daily phone
One's decision on which to rate as most preferred is largely based on the features one would need most. All of us uses our phones differently

My phone usage is mainly ( 80%) on internet based stuffs - Browsing, Facebook, Tweeter, News Feed, Mail, Whatsapp, YouTubes viewing. Other minor usage ( 15%) - Audio, Movies, EBooks, Skype . Calls/SMS takes up the balance usage
I DON'T play any serious games on my phones. But I do test out some games ( eg Asphalt 8, Riptide 2, Need for Speed) solely just to get a feel of its performance

I will use a simple rating : 10 for EXCELLENT and 1 for POOR. 0 is non existent feature

These are my personal assessment and it does not mean I am always right as different users could view these differently from me
Here goes my 5 cents comparison :

BUILD QUALITY : LG V10 ( 9.5), Mate 8 ( 8), Nexus 6 P ( 7)

DESIGN : Mate 8 ( 9), Nexus 6 P ( 8.5), V10 ( 8)

LTE CONNECTIVITY ( CELCOM) : Mate 8, Nexus 6P (9), V10 ( 8.5)

ERGONOMICS & COMFORT IN THE HAND : V10 (9.5), Mate 8 ( 9), Nexus 6P ( 8.5)

DISPLAY : V10 ( 9), Mate 8 ( 8.5), Nexus 6P ( 8) : I had never like Amoled colors as I find them too overly bright and saturated . Again this varies with users. The Mate 8 though is only 1080P does not lose out in any way significantly to the other 2 phones. The V10 has a second display ( can be hidden) at top and is good for quick access to commonly used apps

DISPLAY in BRIGHT SUNLIGHT : Mate 8 (9), V10 ( 8), Nexus 6P (8)

EASE and SPEED OF FINGERPRINT RECOGNITION : Mate 8 ( 10), Nexus 6P (9), V10 ( 8.5)

EXT SD card support : V10 ( 10), Mate 8 (10), Nexus 6P (0) - both V10 and mate 8 can support up to 200 GB cards but I am using only 128 GB on both

USB OTG support : V10 (10), Mate 8 (10) , Nexus 6P ( 7) : Nexus 6P,  you need to root and install stickmount app to recognize USB OTG connection. The Nexus 6P can easily detect attached thumb drives ( up to 64GB) BUT it cannot auto detect those USB dual thumb drives. One would need to install another app USB OTG File Explorer app for that. Both V10 and Mate 8 auto detect USB-OTG by default without the need to root

CAMERA shots quality : V10 ( 9.5), Mate 8 ( 8.5), Nexus 6P ( 8.5) - camera snap speed about similar in all 3 phones. The V10 camera app offers more features and manual mode too

VIDEO SHOT quality : Nexus 6P ( 8.5 ), V10 ( 8.0), Mate 8 ( 7.5)

OVERALL PERFORMANCE  : Mate 8 ( 9.5), V10 ( 8), Nexus 6P (8) - On benchmarking alone eg Antutu, Vellamo, GFX Bench etc the Mate 8 is way up above . However since I do not play games, this doesn't really matters to me

DEFAULT UI SMOOTHNESS : Nexus 6P ( 9.5), V10 ( 9), Mate 8 (9)

AUDIO QUALITY : Nexus 6 P ( 9), V10 ( 8), Mate 8 ( 8) . The Nexus 6P however at maximum volume at certain times only, the sound get slight cracking

CALLS QUALITY : Mate 8 ( 9), V10 ( 8.5), Nexus 6P ( 8.5)

BATTERY LIFE : Mate 8 ( 10), Nexus 6P ( 7), V10 ( 6) : The Mate 8 with its 4000 mAh battery is only 33% larger in capacity vs V10 and 23% vs Nexus 6P BUT its battery life is close to 67% higher vs Nexus 6P and double that of V10
I had repeated achieved 9-10 hours SOT on the Mate 8 vs 5-6 hours on Nexus 6P and 4-5 hours on V10. However V10 has advantage of replaceable battery if the need arises

OPERATING TEMPERATURE : Mate 8 ( 10 ), V10 ( 8), Nexus 6P ( 8) : Mate 8 remains cool even under continuous usage up to 2-3 hours. Phone just feels very slight warm only

ROMS FLASHABILITY : Nexus 6P (10), V10 ( 3), Mate 8 ( 3)

FIRMWARE UPDATE : Nexus 6P ( 10),  Mate 8 (5), V10 ( 3)

EASE OF ROOTING : Easiest is Nexus 6P while the Mate 8 and V10 one need to get an unlock code first from the manufacturer

For my usage, I rate in this order : LG V10> Mate 8 > Nexus 6P

Tech specs of these phones :

LG V10 : http://www.gsmarena.com/lg_v10-7606.php
Nexus 6P : http://www.gsmarena.com/huawei_nexus_6p-7588.php
Mate 8 : http://www.gsmarena.com/huawei_mate_8-7239.php

Please feel free to ask if you have any specific questions on these 3 phones