Pssst, that one Super Santum TD does. There's a lot of TD games that do.
Orcs Must Die, Sanctum and Dungeon Defenders all allow that, but those are the combat focused ones. So maybe not your cup of tea.
Rise to Ruins is a great TD game that mixes in City Builder mechanics which allow you to create any Tower path you desire. Keep in mind though it's as much a City Builder game as a TD game.
Prime World Defenders has elements of creating paths. It's an older game but I really enjoyed it.
There's a demo for FrankenStorm TD that is a roguelike create a path of towers TD. It's actually pretty good. The game is supposed to release sometime this year. I put in 30 hours just in the demo.
I've played so many TD games it's hard to remember all of the ones that allowed you to create paths for the enemies.
Regards,
SB