Becker one of the best
Becker had the total package: potent serve (a major weapon); excellent groundstrokes; excellent volley and overhead; great return game (he would drive his returns compared to Edberg's chips); great athleticism, even though speed was only average.
He could play from the baseline against Lendl, and volley with McEnroe or Edberg, and serve and return better than any of these great players.
I'd say the period from 1985 to 1995 produced a fantasic array of great tennis players. Some, like Connors and Mac, were at the ends of their careers, but still competing well. Lendl, Wilander, Edberg and Becker were all great champions; while there were many other excellent players (Mecir comes to mind) playing during the mid to late 80s. Sampras, Agassi, Courier, Chang, Muster, Stich, Kraijcek, Brugera, and many other great players matured during the early 90s.
The competition was tough, but to me Becker was the most complete player. I'd rate him third after Edberg and Mac as the best volleyer of all time; and he could hold his own against Lendl and Wilander from the baseline. He had a better serve and return than Lendl or Edberg. He was a great athlete, if only average in court speed. Becker's volleys were much more potent and natural than Sampras's.
For sure, Becker had the talent to win ten grand slam titles, even against the great players of his time. But he set one record, winning Wimbeldon at age 17, that will probably never be equalled, much less broken.
Becker was the most complete player the game had seen since Rod Laver, and although Federer moves much better than Becker he doesn't play the net nearly as well. Becker is better than than his Grand Slam record indicates.