I typically use a Garmin 500 and 800. The 500 I have to use my reading glasses to see the data. There are times when bright sunlight makes it difficult to see either of the 500 and 800.
As far as experience with other displays I have used my iphone with a ANT+ wahoo case and wahoo app as a backup when I had to send my 800 in for replacement and the display is much better, but the battery was not that good for a longer efforts. The last time I used my phone the battery went dead 10 miles from the end of a 60 mile route.