Well realisticaly there is only a limited number of "availible" ladies living on such an island so the choice is restricted from the get go. The ladies on the island are as follows...
Rose - Married Claire - had a thing with Charlie... Sun - Married Shannon - had a thing with Sayid Libby - had a thing with Hurley Ana Lucia - AVAILABLE Kate - AVAILABLE Juliet - AVAILABLE
Each of the single girls has a quality that appeals to both the guys. Jack likes Kate because she fixed him after the crash and they immediately bonded. Sawyer likes Kate because they are both outcasts in their own way. Jack likes Juliet because the two are similar in the way they think, their profession and she makes a mean cheeseburger. Sawyer is attracted to Juliet because she's "got his back" and they went through the time travel experience together
They are similar in some ways, but I don't think they like same girls! Kate was only girl on the island with who they communicate and Juliet was only girl who was left on the island after oceanic6 rescued. Also Jack didn't like Juliet much. If there were zaidi free girls in Lost they would like different ones