In the last 10 years, there have been some terrible title reigns (The Great Khali's WHC reign, Dean Ambrose's US Championship reign). However, there have also been some amazing title reigns. Here's my list:
John Cena's third WWE Championship reign (September 2006-October 2007 for a total of 380 days)
CM Punk's second WWE Championship reign (Survivor Series 2011-Royal Rumble 2013 for a total of 434 days)
Sasha Banks' NXT Women's Championship reign (NXT TakeOver: Rival to NXT TakeOver: Brooklyn for a total of 192 days)
Bayley's NXT Women's Championship reign (NXT TakeOver: Brooklyn to NXT TakeOver: Dallas for a total of 223 days)
Randy Orton's second WWE Championship reign (No Mercy 2007 to Backlash 2008 for a total of 203 days)
Hiroshi Tanahashi's fifth IWGP Heavyweight Championship reign (Wrestle Kingdom V-The New Beginning 2012 for a total of 404 days)
Kazuchika Okada's second IWGP Heavyweight Championship reign (Invasion Attack 2013-Wrestling Dontaku 2014 for a total of 391 days)
John Cena's third WWE Championship reign (September 2006-October 2007 for a total of 380 days)
CM Punk's second WWE Championship reign (Survivor Series 2011-Royal Rumble 2013 for a total of 434 days)
Sasha Banks' NXT Women's Championship reign (NXT TakeOver: Rival to NXT TakeOver: Brooklyn for a total of 192 days)
Bayley's NXT Women's Championship reign (NXT TakeOver: Brooklyn to NXT TakeOver: Dallas for a total of 223 days)
Randy Orton's second WWE Championship reign (No Mercy 2007 to Backlash 2008 for a total of 203 days)
Hiroshi Tanahashi's fifth IWGP Heavyweight Championship reign (Wrestle Kingdom V-The New Beginning 2012 for a total of 404 days)
Kazuchika Okada's second IWGP Heavyweight Championship reign (Invasion Attack 2013-Wrestling Dontaku 2014 for a total of 391 days)