Lets do it feature by feature.
Display
LG G6 - LG G6 has a great QHD quantum LCD display @1440 x 2880 pixels with high colour accuracy and fidelity. Brightness and contrast are great too. Top quality panel made by LG themselves.
Nokia 7 - The 7 plus also has an LCD IPS display but at a lower 1080 x 2160 pixels pixels. This is also a good panel, but as the numbers indicate, it offers lower pixel density compared to the 2K panel on the G6. However, you will be hard pressed to tell the difference in day to day use unless you do a lot of high resolution photography/video or use VR apps often.
Storage
The G6 has a faster UFS 2.0 storage, which is fast compared to a basic emmc type storage found in most mid range phones. The type of storage impacts day to day usability with faster storage like UFS feeling ever so slightly faster in opening apps or editing videos/clips. Copying to and from the storage will also be faster compared to the emmc type.
Nokia 7 - Has a standard emmc 5 storage which is what you get in most phones under 300 gbp. It is still a good storage, but falls behind the UFS storage on the G6. Day to day usability will be absolutely fine unless using disk intensive apps.
Performance
LG G6 - The processor used is a Snapdragon 821, a high end unit used in premium phones launched in late 2016/2017. It is very fast and capable of tackling any app or game out there. The GPU is the powerful Adreno 530 which is great for gaming and heavy editing.
Nokia 7 plus - This uses a newer but lower range Snapdragon 660 processor, with an Adreno 512 gpu. Although not flagship class, this is still a very good processor and matches anything out there apart from the 800 series processors. Performance will not be an issue and you mostly will not notice the difference unless you are gaming or doing processor intensive tasks such as video editing. The phone flies due to the use of stock android.
Battery
LG g6 - the G6 has a lower battery capacity with a more powerful processor, which means battery life will be about average. The Snapdragon 821 in the G6 is also more power hungry due to a bigger GPU and memory. The high resolution display contributes to higher power draw when the display is on. Having said that, unless you are a heavy gamer or photographer, you should be able to go 1.5 days without a charge with reasonable usage.
Nokia 7 - This has a bigger battery, a more battery efficient processor and a lower resolution display, resulting in seriously good battery life. It has one of the best battery longevity in its segment and you will not be rushing to charge at least for a couple of days with normal usage. If battery is a priority for you, the Nokia 7 plus is a better choice. Th
Camera
LG g6 - The G6 has a better camera due to a larger aperture camera, optical image stabilization and a better sensor. It takes very good pictures in standard lighting and does the job in lower lighting. The OIS helps in countering shaky hands in stills and videos. You have a host of manual settings as well with the ability to save images as RAW files for editing. The secondary rear camera is a wide angle lens which you can use to take photos with much wider fovs. Overall it is a capable performer with two good rear cameras. The Selfie cam is just about OK if you are a lover of selfies.
The Nokia 7 plus has a good camera as well but does not offer OIS. The aperture is 1.7 for the rear cam, the same as the G6. The secondary camera offers 2X optical zoom which allows you to take pictures at longer distances without fidelity loss. This is different to the G6 which has a wide angle secondary camera. Pictures are good, but not as good as the G6 due to lack of OIS. Similar to the G6, you can switch to a manual mode for more control over iso, exposure, metering etc etc.
The 7 plus has a much better selfie camera, if you are so inclined.
Software
LG G6 - This has LG's take on Android, which is pretty good in my opinion. Its one of the more user friendly UIs out there and not radically customized like Huawei or Xiaomi phones. The additions made by LG are mostly useful and add utility rather than bloatware. This also got the Oreo update so all good there.
Nokia 7 plus - One of its bigger selling points is the fact it comes with pure android oreo with very little bloat or unnecessary duplication of apps. Its smooth as butter and is guaranteed to get updates for at least a couple of years as it is a part of the Android One programme. The fast processor plus stock android makes for a smooth user experience.
Waterproofing
LG G6 - This is IP68 waterproof, which means it can withstand FULL immersion under water for half an hour, upto a couple of meters. Which means you can shower with it or even hit the pool, not to mention the fact that accidental splashes will not damage it at all. Imo this is a big plus in its favour.
Nokia 7 plus - Unfortunately is not waterproof. Build quality is otherwise fantastic. Good looking phone.
Lets summarise.
If you want a good camera, fast processor, stable software and high end display and water resistance, go for the G6. It also has great audio output and looks smashing.
If you value battery life, smooth UI, large screen, decent camera and an efficient processor with stock android software with guaranteed updates for the next couple of years, I recommend the Nokia 7 plus.
Both are very good phones and will serve your needs. You can take a call on the basis of what you prioritise more.
