Purchase advice Mazda 6

Hello, I have at the moment a BNMW e36 320i coupe, now a bigger car must come from, I thought of a Mazda 6, wanted to ask now what you think of the car and what weak points the 6er has ? and which engine would you recommend me, wanted actually the 2.3er, but now I heard that he pulls from below net so well and has little torque and that the diesel engine should have much more torque! which diesel is better, I have to take then 2 liter diesel with 143Ps or r is enough with 121Ps. and which would you prefer the “old” or already the facelifting model with 6-speed. …thank you already in advance!!