#1 The Miz (15 titles)
Despite the excellence of a lot of names already on this list, one man stands alone with the most championships between 2010 and 2019 -- The Miz. It started when he waltzed into the decade as the United States Champion.
By the end of 2010 itself, The Miz was the WWE Champion. While his reign was not entirely memorable, the A-Lister can still claim that he defeated John Cena in the main event of WrestleMania.
A female WWE star said her life is in danger. Details HERE
Aside from that, The Miz captured the WWE Tag Team Championship four times and most notably, the Intercontinental Championship eight times. It was his time as IC Champion in the latter years of the 2010s where the Awesome One truly proved his worth as a top tier Superstar in WWE.
He won every possible title over the decade and perhaps shockingly, has been a champion every single year in the 2010s. So despite a poor 2019 for him, The Miz truly had an awesome decade.