Of what you originally listed I'd go for the 19 for the sights and magnum capability. I really don't get the thing about magnums beating you up out of a K frame. Personally I think the K handles them just fine. While I voted for the 19, I'd personally go for a 66 for the ease of maintenance.

The desire for a new gun is understandable. Just be aware that S&W quality control has truly been erratic. I've seen several NEW S&W revolvers in gun shop show cases that were clearly defective. A new gun needs to be inspected very carefully, as well as a used gun, hopefully by someone that knows their stuff on what to look for.