Racket for Singles/Doubles ?

I would actually say Yonex Voltric 70. It's quite light making it good for defence, and also has a medium-flex shaft to help you generate more power. It's also often heralded as a doubles racket; and is also suitable for singles.

 

I agree with ThomasJE, the voltric 70 is a superb racket for both doubles and singles. However, if you were to choose one of the rackets out of the four listed above, I believe the meteor x80 is your best bet. It's light enough to defend and the shaft, although stiff, generates good power. It's also head heavy, but it's not noticeable on your arms, which makes it easy to handle. My friend enjoys using it for both singles and doubles, and his style sounds similar to yours, although he tries to play control sometimes Hope that helps

 

i've only trained for a short period of time and i can say that the time and money spent on training is for more important that what you've spent or will spend on researching and buying a racket. second, i think you should stick to one racket even when you are playing singles and doubles, especially with the rackets you've listed because i think they are all powerful enough to provide the long shots in singles, but light enough to provide you the quickness you need in doubles.

regarding power, i think if you improve the way you hit, the mechanic, that will give you the most power. the effortless comes from practice, the more you practice, the more memory your muscle will have and soon your arm will execute shots as soon as you thought about it without putting any effort.