Darkstone42
Oh.
If you gave me a choice between Strasburg and Zimmermann, I'd choose Zimmermann. That's for a few different reasons beyond pure ability though. Honestly, I'll take any of the Nats' starters if they're on the market. From a Pirates fan perspective that takes them from contender to one of the favorites. And yes, that's how I'd feel about getting any of their starters...well, except maybe Gio. I'd still be pumped though, he's an upgrade over our 4/5 situation.
Gio would immediately step into the "best pitcher on the staff" conversation with Cole and Liriano, and he'd honestly probably be #1 right now. He's also got the best contract, and is a lefty, so he might be the best guy for the Pirates to actually pursue.
On the other hand, for those same reasons, I think he's the least likely for the Nats to deal. Seriously, his contract is a thing of beauty. Four more years, $11 million in the first, then $12 million in each of the next three, with two of those being option years, and only the final year being a vesting option. I mean, that's unreal value for a pitcher of his caliber, and it's still amazing value if he regresses at the end of the contract to being just average.