I have never had the privilege to own neither an M3 nor an M5.
Both are fantastic cars and like some of the lads mentioned it really comes down to your personal family situation and taste. Going to Athlone on my IS while following Philip's M5 and his friend happy in an E46 M3 they both had an acceleration after the toll in Fermoy. The sound of that M5 is one of the best I must have heard so far; as Paddy mentioned the similar tax, its practicability with 4 doors and that sound which gives you a smile every time you turn the engine on would see me vote for the M5 :wink:
P.s. Very nice idea Gar... looking forward to the next one :wink: