My thoughts are that you already have an M3, so getting another one isn't really much of a change. If you were to do that, I would just keep your current one.
I'd rather have the 2008 M3 that I have now over a 2012 Competition package. There's just no discernible difference other that age and mileage.
I would just go for the M5.. I had one on order and cancelled it because I don't want to be upset when they offer the active seats and LED lighting on it next model year. I've already spent my life retrofitting the 2008 M3 I have now to a 2012, so this one is a keeper forever. I just can't see myself going from M3 to M3, so time for the next playing field
. Voted M5 unless the 335 has some sort of sentimental value to you would is also a reasonable factor.