You should not have a favorite part of your story, as far as writing goes. You can have a favorite part of the plot or favorite character, but if you have a favorite bit of prose, that’s generally not good. Your favorite piece of your own prose probably falls into one of these two categories:
1. The piece of prose is actually bad and you need to cut it, Mr. Purple Barney McGrimacePrune. A lot of people are amazed by their own grandiloquent wordings. English teachers convince them that to make a great story, all they have to do is call a tiger’s fur amber instead of orange. Look over your favorite bit of prose and ask yourself whether it’s necessary and readable. Does it really add something, or is it just a way of patting yourself on the back for being clever at the expense of your readers?
2. The piece of prose is good and you need to make the rest of your story just as good, Sir Lazy O’SitsOnButtocks. Use that part as the standard to measure all your other parts against and don’t stop editing until the other parts are just as good.