The bid for "Greatest" Mansion in the entire series probably comes down to Arthur Kennicutt's impressive spread (The Beverly House) or Fielding Chases's ostentatious "elevator" ride and extensive property.
I like that Tudor house too in Forgotten Lady. Alex Benedict's Pasadena mansion was something tho wasn't it but I like old school. The ONE house I would love to live in tho would be Dr Mason's in How to Dial a Murder. Love Old Hollywood.