whichever you like. The racket you feel most comfortable with should be used for all situations IMO. Determine which you like better, and use that onwards.
They're both fine for any kind of play you want, if you're comfortable with one racquet it's fine for everything.
I don't think that is helping him much... I doubt he has access to enough funds to buy both and test them out, and I don't know if he has any place to go to test out either of these rackets, so I doubt saying "whichever one is comfortable" will help him =P As for your actual question deathsticks, I suggest you search "arcsaber 10" and "NS 7000" on the forums, I am pretty sure there are plenty of reviews by people who are fairly qualified to provide you with insight
well, i own both. and use both regularly. Arc10 is much more power, and if thats how you want to play, a mix of control and power, go for it. NS7k is more defensive oriented, and if you like to drop more, itll fit you better. but you can smash with it. its not thaat bad in the power department. if you are in san jose...well, i guess fremont UBC is a bit far, but otherwise i wouldnt mine letting you try.