Open world games are the leading genre in gaming. Accept it or not, they are the sales juggernaut of current gen. GTA 5 sold 75m. Horizon: Zero Dawn sold 7.6m solely on its strength as an open world game, as no linear single player new IP can sell that well. BOTW is the best selling Zelda game despite its status as a Switch launch title. That is a feat only an open world game could achieve.
As a result of this success the open world genre has become active and the vast majority of AAA single player games are open world. So in this competitive genre of games what is your favourite? Red Dead Redemption is my favourite because of the amazing open world that Rockstar crafted, which feels alive and real but is designed with gameplay in mind and is smaller than a lot of open worlds but feels bigger because of its design.