Part of it depends on genre. First person is popular in mystery and chick lit (assuming there's still chick lit being sold). Omniscient is popular in literary and humor/parody (Terry Pratchett and whats-his-name Fforde).
Otherwise, third limited is a safe bet. There are significant numbers of readers who dislike first person (and even more who dislike second person), and won't even consider a book written in that POV. I haven't heard of a similar pool of readers who turn up their noses at third person, and while I'm not sure they'd all be able to identify the difference between limited and omniscient, except that they might pick up on the distance in an omniscient POV, and come up with the conclusion that they just didn't bond with the characters, something that tends to be important in popular fiction.
JD