GPS + GLONASS or GPS + Galileo or only GPS ?

Some of the factors that could affect the accuracy of GPS include:

• Walls, tall buildings, vehicle roofs or other obstructions blocking GPS signal

• Crowded area

• Poor network connection

• Rainy weather

• Metal

I don’t think you understand how GPS works.

No one place in the world is going to give you a consistently better GPS signal than another place provided there is an unobstructed line of sight between the receiver and the four or more satellites needed for your location to be established. What does matter is which satellite constellations are overhead at any given time, but since the satellites are all in different orbits the strength of the constellation fix will vary day to day from the same location on Earth. Hence there is no straightforward answer to your question.

In the future I’m hoping the watch will be able to detect which constellation combination out of the three has the most satellites overhead at any given time and location and it will automatically choose the best setting.

Like I say only United Kingdom experience advice please Is anyone from UK here ?

If I remember correctly, scotthunter2 is from the UK.  I'm not sure what you're looking for as everyone here has answered your question.  For some reason, you won't accept those answers. Best of luck Tom2020. 

As mentioned by others, the best combination at any given moment/location can be different. I’m not sure if the number of each satellite is a perfect proxy but in the absence of signal strength (which apparently the Fenix had before the F3), here’s an app that shows how many of each type of satellite is visible in real time in your location:

https://apps.apple.com/us/app/gnss-view/id924350018

As you see, it’s for iOS - I’m sure there are Android alternatives. After you open this app several times, you’ll see how the satellites seen from a given location shift over time.

Absolutely agree with scotthunter’s suggestion for the best combination to be automatically selected by the watch at the start of each activity and I would wait a bit longer for the GPS lock for this functionality.

Disagree from my perspective, I’m in the Uk and for running, hiking and walking my more accurate distance, pace or map path

1. GPS & GLONASS 

2. GPS
3. GPS & Galileo 

as you can see, different people have different answers and depends on so many factors already mentioned in this thread.

i think it’s pretty rubbish that we need to choose, the watch should have a fixed or automatic option, the automatic bring a table of best gps system for your location for a rolling 30 min window and constantly switch between. This also should cover China and Japan gps systems and any others the chipset supports.

sure Garmin can depriorities if they have not optimised them for the watch...

South east England. But as I say it’s all a bit random depending on time of day, gps constellations. I’ve never really worried as it’s good enough.