BMW or Hyundai?

I’m looking to Buy a new car pretty soon cause I got a decent job, my problem is how different my choices are, I’m trying to decide between a new Elantra N and a used 340i or 440i at a similar price, I like how many features the Elantra has, specifically the suspension, exhaust, and steering adjustments. and I really love the styling and appreciate the warranty. I’ve only heard glowing reviews for it too. I own an e90 right now that I love, amazingly fun car too drive, so I really like the idea of the bmw, especially a b58, but it feels kind of like an immature decision maybe? I can’t even articulate it really but I can’t help but feel like that. Is there something I’m missing or a way to think about that might elucidate the decision a bit?

Are B58s really as reliable as they’re made out to be, or can they just handle a lot of boost?