Those are all great colours. I loved Steel grey, you rarely see that colour though. A lot of the 2001s to 2003s were Titanium Silver, people didn't seem to buy greys back then. Silverstone is my fave E60 M5 colour too!
Both my 330Ci and M3 are Silver Grey. The only reason I bought my M3 is because while driving my 330 I had always told myself there's no way I'd get rid of it unless I found a Silver Grey with Competition pkg and 6 speed. Comp and 6 speed is super rare, but then a leased one got dropped off here and I told myself I had no choice but to buy it. I'd be totally happy with Interlagos Competition pkg too, IL Blue is ultra rare on the M3s.
Hope you enjoy your car.