I can't recommend Carenado's B200. Sure, it's a wonderful model with beautiful textures but under the hood it's just the FSX default King Air. The Flysimware Cessna 441 is quite the opposite: An excellent systems depth but some very poor textures.
However, if you ask me the best turboprop twin right now is RealAir's Turbine Duke v2! One of the best flight dynamics, a wonderful model and a very good simulation of the systems. Or if you are looking for a King Air B200 I would choose Flight1's great Super King Air.
Greetings
Tim