I agree with Borg and Lendl.... but see it as a bit of a moot point
Lets compare Lendl with Pete Sampras
Lendl.... serve, return, forehand, backhand and (contrary to popular opinion) volley all top notch.... that's pretty much everything
Sampras.... the return and the backhand at least not of top drawer
So can we conclude Lendl > Sampras?
Of course not!
The whole is not the sum of its parts
-----
Re: intergenerational comparisons.... I'm of the opinion "ability" in one era would likely translate to another
The moderns don't come to net much its true.... but I reckon if they'd been from an earlier period, they would have
Likewise, if the likes of Laver and Rosewall had grown up on graphite and poly strings, they'd probably play in the style of today's players; baseline stuff.... why come to net against the blistering passing shots todays racquets allow all and sundry to play?
They say Nadal would have failed on grass in the old era.... maybe he would, but
I'm absolutely certain that if Bjorn Borg played today, he'd be an out and out baseliner, and they'd
all say the same thing, he couldn't have cut it on old grass. and we all know what he actually did on 70s grass
Lets try to judge players in the time they played in
Hard to imagine John McEnroe playing as a baseliner, or Novak Djokovic serve-volleying all the time at Wimbledon, isn't it?
----
Anyway, most complete players I know of.... Borg (volleys not so great), Lendl (all there, maybe missing attacking instincts some), Jimmy Connors (serve is a handicap) and Roger Federer (not sure how he'd do grinding on clay with a wood racquet)
Of the lot, I'd name Lendl as the top guy