I voted Bridcutt but you could make a case equally as strong for Murray. Dicker is quality when he is firing on all cylinders but has been more prone to an occasional poor game this season than the other two, IMO.
Better player = Bridcutt
Most valuable for next season = Murray
Not easy to replace a 20 goal a season target man centre forward. Bridcutt is an outstanding player but if I had to choose the one that is most important to keep hold of it would have to be Murray. If we lost Murray and didnt replace... catastrophe. If we lost Bridcutt and didnt replace.... potentially got cover there in the shape of Navarro.
Going on the 'harder to replace' valuable than the 'monetary' valuable i'm gonna say Murray is more important, however it'd still be a disaster to lose Bridders as he is going to be a star!