2Bravo already touched on the fact that crews work so close together, and you become very tight knit.
To me, it was the shock of seeing (and hearing) a Centurion tank firing while my father was posted to Petawawa in the 60's. There is absolutely nothing like firing sabot down range, and seeing the awesome destruction it is capable of. I have never regretted joining the armour, and I will never forget the friends I have made within the family. Yes, we in the Armour refer to the Corps as family.
I know we (Canadians) will probably never again see hundreds of tanks massed together as part of a exercise involving a dozen armour divisions, but it is a sight that will never be forgotten by those who have seen it. Tanks are, simply, impressive in every way, shape and form, especially when crewed by a good crew, and commanded by competent leaders.
Alas, the tank is a dying breed in Canada's Forces.