I am a fan of my Oukitel WP 19 i ordered from China online.
21000mah battery lasts a week (or two)
Smartphone that is able to fulfill its purpose to stay charged, being able to call and use all the different online messangers without fear it will run out of juice during my walk outside (even if i went with only 10-20% charge out of home)
Comfortable to read books too.
And price is very affordable. 350 euro (+around 20% for trans border taxes at my country)
As a modern android it is compatible with everything and having rich ecosystem accordingly.
The only small downside that is a brick with a weight of half kilo at least.
My second one after the first was returned to google two years in and they declared it beyond economical repair. (Defective hardware). They replaced it for free so I guess I'll be using this one till it dies in two years time too lol