Do you really want the first model year of the new M3/4 or the last model year of the E92? Personally, I'd go for the last model year E92, since it has all of the kinks and problems worked out. Who knows what will crop up with the new M3/4?
As for whether to use it as a DD or not, the community is somewhat split. Some (like me) use it as a DD rain, shine, or blizzard. Others have garage queens. Just depends on what your needs and wants are. But the E9x M3 is a great DD car, gas mileage aside ...