It looks like there are differences between this spreadsheet version and website version. On the spreadsheet there is one reign that is not on the website (16/04/1904 - 22/04/1904) and website has 4 reigns that are not on the spreadsheet

Teams with the most title reigns:
1. Aston Villa: 47
2. Blackburn Rovers: 41
3. Everton: 37

Teams with the most matches played as current champion:
1. Blackburn Rovers: 129
2. Aston Villa: 124
3. Arsenal: 115

Teams with longest combined time as champions:
1. Burnley: 2717 days
2. Ipswich Town: 2411 days
3. Blackburn Rovers: 1781 days

Hey, I created this account just to write this. I'm in the process of converting website data to JSON file to easily find info like this. It's not fully ready yet, but according to my quick research, the last change of leader happened 3/3/1934 when Aston Villa surpassed Blackburn reaching 92 wins