I would prefer to take off one player from each team after 90 minutes and allow 1 additional sub to made, but only in the interval before extra time. So you get to take off 2 players and introduce a fresh one. If still a tie after 15 mins, another player per team is removed. At the end of 30 mins extra time, number of shots on target determines winner.
This means a team can't play defensively, coaches substitution decisions will be more considered, fitness will play a big role and there should be more excitement.