if you're doing 70-100km (and you live in europe
) go for diesel.. performance (0-100) is almost the same, you get more torque, it'll be worth more than 220i and fuel comsumption is lower
i think it's hard to say which one is less faulty.. but I've read somewhere that diesel with 8AT "shakes" the car a little when it's turned on with start&stop function (petrol doesn't)..