It Depends on Intent
I own a 2004 C4S with 40,000 miles and for your purpose, I would choose the 1 series. I drive mine maybe 2 days a week and put 3000 miles a year on it. I just really wanted this Porsche as a third car. For a daily driver, I would definitely prefer the warranty and routine maintenance coverage. I just changed my brakes and rotors myself and it was $900. If you just want a Porsche or can afford a newer Porsche under warranty, go for it. Otherwise, for 40K as a daily driver, go for the BMW. I plan on keeping my car for years and it's not a daily driver. I just feel that it is more of a classic car, and fun, for the long haul. Tenths of seconds 0-60 or or 50-70 are not critical in my decision, although I may track the car at some point. It's all about what you want it for and for how long.