How much do you want to spend. The Tektros that came on my Novara work surprisingly well and can be had for a very low price point. You can find nicer brakes and spend more. Personally, I'd stick with something somewhat close in quality to the rest of the bike or a little better. I wouldn't put real high end parts on a low end bike unless I already had them or picked them up cheap used or something.
That is just one opinion though.