A lot of times when I ask other writers for advice since I am not advanced, a lot will tell me if there is a plot hole, or an implausibility here or there, and they will give suggestions on how to fix it. But I find that a lot of the suggestions can get in the way of the theme. If a character makes a different decision or if something else happens in a section of the story that alone can change themes about feelings you are trying to engage in the reader. One writer I had a conversation with suggested that I change the ending of a story, because he said that the villain's downfall means he would have to make a mistake that perhaps he wouldn't normally make and the his downfall as a result of his 'weakness'. But I was told by another writer that him making decisions based on his weakness causes problems in the plot, and he suggested a new way that was more likely and plausible to happen. He said that the hero should just shoot the villain in the head because then it gets rid of implausibilities. Yes it does, but anyone can be defeated by being shot in the head, and the villain is not brought to his downfall by his weakness therefore. The theme is gone, but the plot may be more plausible as a result. That is just one example, but if you had to pick between what's more important, the plot holding together better, or stronger themes for the reader to get wrapped up in, what is more important if you had to pick one, and could not have both?