Have you had your guitar's action (the distance from the strings to the fretboard), set up for your needs? If not, it might be that the strings are too high. That would cause the F chord to more difficult to play, because you are right next to the nut. That is where you would have to apply more pressure to get a clean sound. If the guitar's action is high off the fretboard, it will be worst on the first fret.... like you are describing.