A good badminton racket for me?

i'm looking for a racket that's not too heavy and too light either... i need one that gives me more power to hit hard... i lack power and i would like one that would help me hit far (until the end of the court) but not too far because it will be outside the boundaries already... i don't mind the brand, but i know yonex is better.. is it better to use a longer racket? and what does the weight 3u, 4u mean? are super light rackets good? or the average weight is still the best? i'm not really a beginner, i'm almost becoming an intermediate player...