List of a bunch of the best free WordPress themes:
Astra
OceanWP
Hestia
Neve
ColorMag
Ashe
GeneratePress
Sydney
Zillah
Shapely
Here is a list of the best premium WordPress themes
Divi
Avada
Enfold
X Theme
The7
Flatsome
Bridge
BeTheme
Jupiter
Salient
If you would like to have my recommendation then the best free theme I would suggest is Astra and the best premium theme I would suggest is Qwery