Just to start you off, I would buy an Audi A3 or a Mini Cooper S instead of the 1-series. Enough said about that.
3-series: I would recommend the 335i or the 328xi, because they both have great technology, around the same price, and have good MPG. If you need an alternate recommendation, I would say a Cadillac CTS would be a decent replacement, but buy the BMW.
5-series: I love the 5-series. It is SUCH a great car. The ride is great, the performance is great, and it has great safety. I would recommend the 528xi. However, I would probably end up buying the same-priced, slightly less fuel-efficient, but definitely more fun, base Chevrolet Corvette (yes, they are owned by chevrolet).
6-series: If you're going to spend that much money on a car more expensive than a Lexus IS-F, and won't get the performance OR MPG, hen spend more and buy yourself an M6.
7-series: Buy a Nissan GT-R instead.