Which name do you like better? Me, I like Uncle Pennybags b/c it is the original name and sounds better IMO. I don't care what Hasbro says, I will still call him Uncle Pennybags. Here is a little history about the character.
The unnamed character made his first appearance outside of Monopoly within the Parker Brothers' game Dig, released before the U.S. entered World War II. The character did not receive a name until 1933 when the game Rich Uncle was published by Parker Brothers. His likeness appeared on that game's box lid, game instructions, and currency.
A more contemporary depiction of Pennybags on the box of Monopoly
Between 1985 and 2008, the character appeared in the second "O" in the word Monopoly as part of the game's logo.
In 1988, Orbanes published the first edition of his book The Monopoly Companion. In the book, all of the characters that appear on the Monopoly board or within the decks of cards received a name. Uncle Pennybags' full name was given as Milburn Pennybags, the character "In Jail" is named "Jake the Jailbird", and the police officer on Go to Jail is named "Officer Edgar Mallory".
In 1999, Rich Uncle Pennybags was renamed Mr. Monopoly.