There are three options really:
Brew sugar
Enhancer
Spray malt
Sugar just helps you increase the % but doesn't add any flavour or body. Enhancer is essentially a mix of sugar and spray malt and will give more body and flavour. Malt is (in my opinion) the best bet.
Pick the dried spray malt colour that is closest to your beer style and brew away. If you can't get that, the enhancer will brew you a better better than sugar alone.
That said I brewed a good few kits with just sugar and they all tasted nice and got drunk.