Both quote close together price wise now , not sure which is best!

I like the map space that the 810 has but screen isn’t that good and it’s old tech now?

520 has clearer screen, bit more hassle loading maps but will be supported by Garmin for longer. Not that bothered by strava segments.

What does STW think?

520

Also interested in this. Given up on my 510, it’s being sent away to Garmin to exchanged for another new one (2nd in six months) so thinking of selling it when I receive it and put the money towards a 520/810.

Had the same dilemma couple of months ago. Went for the 520 for the same reasons you mentioned: sharp maps, newer tech, buttons rather than touch screen, size. The maps from Talkytoaster are good and quick to install what you need.
I miss the mapping functionalities however from my old 605. If you need the mapping, zooming in/out the 810 may be better

I have the 520 segments turned off, maps loaded. I like it for its clean design and find it perfect for my kind of riding which is generally head down full gas on roads I know with just a couple of screens loaded with a four or five metrics.

The map screen is small and I actually found the old 200 easier to navigate with due to its simplicity, its possible though I could change the settings to make it easier just about everything on these changeable in the options. The mapping is screen is perfectly clear when stopped but too small for me when riding at pace my eysight isnt great though so suspect it would be same on the 810.

A friend has the 810 also with maps loaded but never uses them, hes also had lots of problems with it and the design next to the 520 looks old and bulky for the screen size.

Depends what your looking for if its a week away touring an unfamiliar area I would use my phone and a paper map for navigation. Mapping on either Garmin will be sufficient to work out and follow new local loops, the 520 will be less of a brick on your bars.

I’ve got the 810 loaded with talkytoaster maps and I use it mostly on the road. I love being able to load a route on there and get turn-by-turn directions in new areas – there have been a couple of bugs with this but it mostly works well. What I can’t really use it for is navigating on the fly – the screen is too small to get enough details to make good decisions and I find it generally find it less hassle to just stop and use my phone.

Having not used the 520 I would guess it does the turn by turn thing just as well and probably isn’t too dissimilar to the 810 fo navigation. The only advantage I can really see for the 810 is having more screen real estate for numbers if you like that kind of thing.