I guess that we have to define complete. By complete, I think of a player that was arguably a top 30 guy in history in nearly every category at some point during his career, which includes net play, serve and volley,serving, return of serve, forehand, backhand, endurance, court position, etc.
For today's player, I'd easily take Federer. The big reason here is that Federer has beaten an all-time great like Sampras using a completely different racket while playing a different of game on a different surface. For example, Federer serve and volleyed about 80% of his serves against Sampras, yet still beat that legend. And he beat him on the super-fast old grass while using an antique 85 inch racquet, same as Sampras' at that time. Federer later morphed into a great base line player too. After that, he started going to the net more, which really messed with guys like Murray and Wawrinka in the mid 2010's, despite being an old man. Fed's return of serve on those fast surfaces was amazing also.
I never did get to see guys like Laver play. But I would assume that we was very complete. I only saw Borg for a bit when I was too young to understand the nuances of the game. But he had to be quite complete. I'd put Lendl in there too, although he was more of a base line player. However, he started coming to the net more at Wimby and actually made it to the finals two years in a row at that event.