I don't know that I've found myself pining for any players across Merseyside much over the past few seasons; Marouane Fellaini was interesting before I actually paid attention to his style of play, Mikel Arteta was classy but not overwhelming, and it was hard to actually appreciate Tim Cahill's influence because it seemed as though he so often managed to exert it against Liverpool.
Envy is certainly something we're all prone to, and maybe it's because I'm just supposed to not like anybody associated with them (even though this year it's not really possibly to dislike them too much given the tremendous support they've provided regarding Hillsborough), but rarely do I feel very strongly about anyone who's plying their trade on a regular basis at Goodison Park.
I'll go for Leighton Baines, which is probably the easy answer, as he'd provide quality and consistency at a position that's seen far too much turnover and far too little stability for nearly a decade. He keeps himself fit, is good at both ends of the pitch, and his delivery from set pieces would add an element to Liverpool's play that, Luis Suarez aside, hasn't been too overwhelming this season. Jose Enrique doesn't just get chucked overboard, especially with improved form in the latter half of the season, and the presence of another high quality fullback would provide healthy competition.