Assuming salt means sodium chloride (NaCl, table salt), then a given mass of water can dissolve a larger mass of salt than of baking soda.

Interestingly though, the solubility of baking soda greatly increases with the temperature of the water, from ~6.5 g per 100 g of water at 0°C (32°F, freezing point of water) to ~20 g per 100 g at 100°C (212°F, boiling point of water). Meanwhile, the solubility of sodium chloride stays relatively fixed at ~36 g / 100 g.

The reason that either of these compounds dissolves in water is that they are both made up of charged components called ions which are attracted to the positive and negative parts of water molecules. For example, the positive sodium ions and negative chlorine ions in NaCl salt are more strongly attracted to the negative oxygen and positive hydrogens of the water than they are to each other, and so the salt gets pulled apart.

If by "better" you want faster instead of more, then these answers already on ScienceLine may be of interest. Both of these would be easy experiments to try at home as well.