GURPS is very good for tactical fantasy or historical medieval combat with relatively small numbers of figures, if you learn and use most/all of the advanced rules.
Well, it's good for fairly big battles too, if you revel in the detail and don't mind spending hours and hours at it.
For less complexity of the same thing, there's the predecessor: The Fantasy Trip, now out of print but there is an (even slightly simpler) derivative version with modules being published on the web.
I used to play lots of board wargames (e.g. Starship Troopers, Wooden Ships & Iron Men, Squad Leader, Starfleet Battles, etc etc etc etc), but not very much for a long time now - too much time playing computer games.
PvK