If you're still shopping, I think you should find a way to test drive either a Stelvio QV or Giulia QV. (You can
read my test drives, but first hand experience is always more valuable!) They both have a similar flavor with regards to their steering, suspension, gearbox and engine.
To me, the Alfa's feel like they come from the digital age while the E90 M3 is analog. I'm a big steering snob, and I prefer the M3's hydraulic assistance over the Alfa's electric assisted steering. The engines are also opposites, too; low-revving turbo 6 vs high revving V8.
Take stock about what are your favorite attributes in cars, then see if the Alfa has those things!
Personally, I'd keep the M3.
