I've been mulling this one over since it appeared, trying to come up with an answer. But I can't answer the question as phrased. There are no current ballerinas I could rank with Makarova or Fonteyn or Farrell (although I wouldn't put Farrell in the same category as the other two; a dancer who is primarily a Balanchine ballerina is judged by different criteria in my book).
One problem is that I am not comparing these dancers side-by-side. Today's dancers are being evaluated by what I see before my eyes; yesterday's dancers are being seen through the haze of memory. I was a different person when I saw them, and levels of appreciation have been added to my viewing since then. I can't watch a contemporary dancer with the same set of eyes that I wore when I saw Makarova.
Another problem is that there is a sad lack of new, quality works being staged for the current generation. We can only see them in works where they are competing with the memory of the dancers we first saw in those works. The last major "new" work of any consequence, IMO, was Makarova's staging of "La Bayadere." It's difficult for a young dancer to shine in the lacklustre new works being created, which go in one eye and out the other.
It also should be kept in mind that when we remember Fonteyn or Makarova, we are recalling an artist who had reached their maturity. Makarova was almost 40 when I saw her, and had the time to nail down her technique and hone her artistry and expressiveness to its peak. She was a finished product; today's young dancers are still learning. (It's a sad fact of ballet that by the time you've got it all right, it's time for you to get off the stage.)
That being said, there are quite a few ballerinas today that are a joy to watch on their own terms. Darcey Bussell and Viviana Durante, two dancers with very different qualities, are at the top of my list. (Several people mentioned Assylmuratova. I've admired her since I first saw her on video in "Backstage at the Kirov," but can't forget how easily Bussell out-shone her in the "La Bayadere" video.) Susan Jaffe and Julie Kent also rank up there, as well as Nina Ananiashvili. On the Balanchine front, there are Helene Alexopolous, Wendy Whelan, Kyra Nichols, and Darci Kistler. For the future, I also have my eye on Riolama Lorenzo, who I've only seen in the corps at NYCB. She stood out there and shows promise (it helps that she's tall and beautiful and not so scrawny).