Didn't you have a 335i before?
But anyways. I've driven a 335i with KW V1's and it was probably the most planted car I've ever driven, would recommend if you can swing them.
The BMW Performance tune isn't the best value tune on the market at $900 for 20hp, but it also messes with the VANOS timing to make the car burble under overrun, which sounds amazing.
Bang for buck tuner is definitely JB4 and it's also the best for keeping the car friendly to aftermarket warranties, since it doesn't flash the factory ecu.
If its an autobox, the Alpina Transmission tune also makes a BIG difference, don't know how much it costs though and it requires tools beyond a handheld tuner.