Ponty's output has been huge (in quality and quantity). The MPS records before Zappa, the Zappa period, the work with McLaughlin and the first few solo discs that followed brought him alot of well deserved acclaim. Then his records started becoming safe, cliched and predictable. Steve Kindler, Didier Lockwood, and Scarlet Rivera followed a similar path opting to put out mostly Kenny G flavored Yanni-ized products that fail to challenge or stimulate fellow mucisians or other well informed listeners.
Jeff Gauthier's work (tho' probably not everyone's cup of meat) has contributed to alot of beatifully recorded and anything but banal discs, (The Mask, Infernal Memo, Present, or Alex Cline's, The Other Shore). Mark Feldman is another great violinist who has really been going for it musically, he often takes on radically diverse roles as a player and has recorded with John Zorn, Michael Formanek, New and Used, Dave Douglas, Percy Jones (yup, the Brand X bassist), and as a leader.
I haven't heard Eileen Ivers, but believe that all the other violinists metioned in this thread are capable of delivering awe inspiring performances that would make a this one is better than that one type of ranking seem useless and inappropriate. A popularity poll ONLY measures popularity.
PS- Sorry if this reads like a snobby rant, hope everyone has a great Christmas