A 6 speed RWD E90 is the last of the driver's BMWs in my opinion. Even moreso with the last N/A inline 6. That combination is quite tough to find though, especially for the facelifted cars.
I absolutely love my 328i. Get a 2009+ for the facelifted version, it has some issues sorted with the motor and looks a decade newer. They're very fun to drive, fuel efficient, and easy to maintain if you're DIY capable. Parts aren't too expensive vs. the turbocharged motors. No suspension woes like E36/E46, even the cooling system is very stout. Gaskets still leak (typical BMW trademark, lol) but they're easy to do on the N52 save for the oil pan one.
The same N52 engine is found in the 2006 330i (255 HP), albeit it's neutered with the manifold to keep the power down to 220 crank HP. The manifold swap is plug and play, with the connectors already in place on the 328. All you need after that is a tune to activate the DISA valves.
https://www.kijiji.ca/v-cars-trucks/...ationFlag=true
This one would be a great candidate.