Phillips is the most important in my opinion due to how much we struggle without him. No one has managed to reliably replace him without the team balance being negatively effected in some way.
Dallas plays a massive role obviously due to his versatility and consistency however that doesn’t make him irreplaceable. If we sign a high profile left back and centre mid then im afraid that drops Dallas down to a rotation/cover player.
I would also argue Bamford is more important than Dallas for the same reason, he is fine tuned to our No9 role and no other player can fill his shoes.