Age of Wonders: Shadow Magic has an excellent combat system. Too bad the AI is so weak.
Jagged Alliance 2 has a very good system, except the variety of enemies is very limited and the range of weapons is decisive (at least in the beginning).
For those reasons I like (Open)Xcom better.
Baldur's Gate games can have very good tactical combat, partly due to the AI being moddable and thus combat can be challenging. RTwP and no grid means complex battles can become a bit of a clusterfuck, though.
Of older (DOS era) games the Gold Box games are good, but rather limited, with braindead AI.
Disciples of Steel and Nahlakh are my favourite tactical games from that era.
Post edited November 27, 2020 by PetrusOctavianus