The maze is the way to go. Here is a "basic" one. Get on youtube and you will find a lot of other ones!
There is a technique I have mastered call "juggling"; it is making a maze, like my spiral, sending in losts of waves and continually deleting/adding one square to block the ants and send them back the way they have come. That is the only way to get the top scores =)
Looking at my spiral, the very bottom right square can be deleted to send them another direction, then put it back when they get close to send them back the other way!