Some of the later Total Wars, I think personally, that Rome 2 - especially with a game lengthening mod, like say Divide Et Impera - is the best in the series for Head to Head Campaigns, while Co-Op Campaigns are best in Total War Warhammer 2.

They can be relaxing, in that you can let your armies just fight using AutoResolve, or you can control manually - and if you control Manually in a H2H against an AI controlled faction, your Brother can take the role of your enemy.