"If you say Pluto's not a planet, I will cry like a baby"
It seems like the most sensible definition would be one that excludes Pluto, but then there are all these whiners who for "emotional reasons" want Pluto classified as a planet. They learned there were 9 planets in elementary school, and are unable to endure the neurological re-wiring it would take to change that number to 8.
My opinion: screw the whiners. If someone wants to have a highly emotional relationship with a chunk of ice with an eccentric orbit, that's fine. Just don't expect the scientific community to cater to your fetish by twisting the definition of "planet" into something ridiculous.