Congratulations!
I was recently at an event with a couple of pinball raffles and was surprised that everyone who won took a TWD. It's a great game and these are savvy pinball people, so that speaks volumes.
Personally, I'd probably go with either an Aerosmith or Star Trek (assuming it's available). ST because it flows so well and has an addictive quality to it so that I think I could get over the generic playfield. Aerosmith isn't a theme that really grabs me, but it does play well, is probably the best looking machine I've seen, and it would be easy to trade or sell if you got tired of it.
Good luck with the choice!