I own an 08 3900.
I've ridden an older 4300.
Get the 4300. Its better quality, the components are better. And it has disk brake mounts.

If you dont care about that, The 3900 should do fine for city riding. Heck, for city, even a 3700 would do.
My only complaints were the stock parts... =0
They weren't rugged enough to stand up to my abuse.
The Frame itself is decent.