It's always hard to say, because even if I say "Serena is better than Graf because xyz" people will always measure based on titles. I personally think that Serena could be better than Graf. But we also have to take into consideration, changes in the game. Racquet improvements and surface improvements, have allowed people like Serena to flourish even more (more curve on the ball, and much faster play). I don't know if a young Steffi in her prime could stop a young Serena in her prime.
Obliterate? No. The game has changed. A lot faster, a lot more demanding and a lot more physical. Serena is a powerhouse, and on her best days, it's almost impossible for the worlds best to stop her. I'm not saying Graf didn't have any competition at all, but the game is harder these days. There's also much more women in the sport today. The schedule is fuller and more demanding today.
The joke from Agassi was that he doesn't even have the most slams in his household!
Anyway, you're right... which is why I'm adamant on saying you can't compare different generations. The game's changed too much. Like you mentioned, the equipment has been a huge factor. As for the surfaces... I wouldn't say it's faster now, cuz the grass at Wimbledon has become relatively slower since Steffi's days. The bounces are slower, but the ball-striking have been more powerful. Slower surfaces allow for more rallies from the baseline, which is why we don't see the serve&volley players anymore. The game probably feels faster cuz of the equipment and strings. The new strings allow you to generate more spin, meaning you can hit the ball harder, but cuz of the huge topsin, the balls will dip back into the court (instead of sailing past the baseline). That's why we're seeing so many crazy passing shots from way behind the baseline. Guys can whip the ball with huge pace, but they'd drop inside the court at the last second. Back in the day (and I'm saying pre-2000, maybe, pre-polyester strings), if the pros hit the ball the way they do now, a lot of their shots would fly out. Without a doubt the strings favor a certain style of play, which is what we're seeing today.
Steffi held her own from the baseline back in the day (5 French titles, I think?), but also had some variation in her game (slices, chip&charge, volleying, etc) which was how she was able to win 7 Wimbledons. Players back then molded their game to how it was played back then just as how the players are doing so now... lots of running, defense and movement. If the prime-Steffi played prime-Serena in today's conditions, with today's equipment, then chances are, Steffi would lose. But if you swapped and had Serena play on the surfaces back then with a flexible, hefty racquet strung with natural gut, I think Steffi would have the advantage. Hell, if you put David Ferrer up against Rod Laver, playing in today's conditions, I'm sure Ferrer would come out victorious. Having said that, if Steffi grew-up in today's tennis environment, who's to say that she wouldn't train just as hard as all the girls on her movement and defense instead of volleying, slicing, etc? She would just as well adapt her training to accommodate today's style of play. We can't assume that just because Steffi (or all the players back then) didn't play as physical a game, doesn't mean that they can't train to play physically and succeed today.
Sorry for the long-winded post, but I think there are too many people out there nowadays (media, fans, whatever) who conveniently do a straight-up comparison with players from different eras without considering the various factors.
As for Monica... had she not been stabbed, I don't think Steffi would have won as many slams as she did.
