I fear my answer will (in the best case) disappoint the community: there was not a lot of consideration before the purchase. I always had a slight point on Nikon brand name without particular reasons. When I consciously start the photography (it is another story) the choice was obvious and doubtless. Now I can tell the reasons: RELIABILITY. – It is 1st attribute of Nikon in my mind. And the compatibility with old lenses is also important.
As far as other photo brands are concerned --- I profess here the well-known philosophy “the best gun is the gun you have in the right moment”. The rest is obvious. Sorry for heresy, I really respect Nikon and love my camera