what's the best plant I should keep in my bedroom? and which part of the bedroom should I put it in?

there shouldn't be a plant in the bedroom in fengshui; what part of the bedroom? outside the bedroom!
fengshui is not an art of inner peace. it does have many theories, systems and formulas. big reason why you pay a lot when consulting a master. you do not need gut feeling nor intuition in applying fengshui solutions. because they have their own logic. like if there is too much fire, you analyze what kind of fire is it? is it a big fire or a small fire? if it is big fire, then you put a big water or a salt water cure; a salt water cure for a small fire will create too much water! very logical in fengshui terms. no esp needed!
fengshui is not an art of inner peace, because it optimizes one's wealth or health by letting the person accumulate and use the right kind of energy/ chi. it just seems like furniture arrangement, but furniture arrangement is different. in fengshui, rooms/ parts of the house is being arranged to accumulate and maximize the use of good chi to optimize your health or wealth (it is not health and wealth).

Listen, feng shui is an art that pursues inner peace. It does it by arranging the furniture and making it pleasing (to YOUR soul).
What would give me an inner smile as I saw it, would probably not do to the same for you.
This isn't nuclear physics. There is no formula. Try a few different plants in a few different locations. Which one did you like the best? Did any of them make you feel good inside?