Best early Buy Back Hero?

I just won a game by making a critical decision to buyback around the 30 min mark to rat with NP. Reflecting on the game, I began to wonder what other hero in the game can possibly punish you more than NP at that point in the game. I'm pretty sure nothing comes close. There are countless situations where another hero applies, but the pureness of NP rat abilities leaves any other hero in the dust. What do you think?