A few years ago, I did a statistical survey of my success rate with the French. At that time, I scored approximately 70% with it as Black. Not bad, eh? This included wins over one 2400, a few 2200s, and several people right below that rating. Also, a draw against GM David Bronstein (albeit in a simul). And my rating during these years was a solid B-player... 1650-1860 (I say B-player because I spent more time there than in the A category).
I don't worry very much about "success rates" of top GMs because I'm not a top GM. I try to learn and understand the positions, and because I've gotten familiar with them over the years, I play them well, and I would confidently play the French against Kramnik, Topalov, Anand, or anyone else. I'd lose, but I think you play better in openings that lead to middlegames you're familiar with.
Then there is the element of fashion. A few years ago, the French was all the rage, and you would be hard pressed to find a "top GM" who didn't at least dabble in it (Kasparov being the exception, of course).
I think it's a very bad idea to base your openings on what "top GMs" are playing. THat can be an element in your decision, of course, but it is more important to find out where you are comfortable, and go with that. This involves, at least, looking at other openings (for example, I have never played the black side of 1.e4 e5, but I have no issues with looking deeply into Open games, because I think it can add to my understanding of the game). All you need to do is look at the many transpositions from the Ruy Lopez to the Kings Indian. I don't consider the Ruy that tactical, especially compared to the Kings Indian, but you have to know when the transpositions occur, and how to handle positions that do, and don't, transpose. I look at the most boring Queens Indians and the most ridiculous openings, such as the Grob or the Mekele Mobele (I'm sure the spelling is wrong). As long as I can learn something from it, I'll look at it. This is the approach I think everyone below IMs should have. So I don't think it's relevant what "top GMs" are playing this week. Like the weather in San Francisco, it is highly subject to change.
If you scored like that as a B-player with the French then I wonder how badly you did with your other openings to balance that out