If your plan is to pass it on to a child or grandchild, then the most important thing will be the memories of time spent with you that the knife evokes in the mind of the recipient.
The important thing would be "this was grand-dad's knife that I remember him using when he took me fishing" rather than "this is the high quality knife that grand-dad bought with the idea of passing on to me some day."
That being said, get something of good quality that will stand up to the uses you plan to put it through for 50 years. Buck, Case, GEC, Northwoods, Queen, Canal Street, pretty much any of those will do.
Type of steel doesn't matter if you keep the knife properly maintained and don't use bad sharpening techniques that wear the blades down more than needed. Carbon will develop a patina of coloration in addition to the scratches and marks from use and sharpening. Stainless will develop a patina of scratches and lines, but shouldn't change color much. Carbon still will rust if not cared for, stainless much less so but still can.
I'd go with what you want to use for 50 years rather than think about that finish line.