According to many haters, the toughest period in tennis history was from 2014-2016. This period featured peak Fed, peak Nadal(peak clay from 2015-2016), peak Fognini, peak Djoker, and peak Murray. All of the rest of the years since 2000 need to be excluded. With that being said, here are the best players during that period(and therefore, since 2000):
#1. Djokovic: He won 6 slam titles during this toughest period of tennis in history. He wins huge.
#2. Stan: He won 3 slam titles, which includes beating Djokovic en route to hoisting the big trophy all 3 times
#3. Murray: 1 slam title
#4. Nadal: 1 slam title
#5. Cilic: 1 slam title
#1000: Federer
Federer didn't win a single slam title, or even a WTF. Federer played slightly better in 2017 than he did in 2016, but was completely owned by Donskoy, Fed calls Donskoy his daddy now.
Anybody that calls Donskoy his daddy cannot be better than Stan, or anybody else in the top 100. Legend has it that Roger is only the 4th best tennis player in his immediate family. His wife and two girls can destroy him.