There really is no "best" salt. Everyone likes something different. You need to find what works best for you. Best is very relative when it comes to salt. Many people will say that Instant Ocean and Reef Crystals is the best, while others say that Oceanic or Tropic Marin are the best.
It is all a matter of testing your water parameters that your salt gives you and adjust accordingly. If the salt becomes too much of a hassle, switch to a different one.
I have been using Oceanic for the past 3 years and I love it. It gives me excellent calcium and magnesium, dissolves quickly, has good trace elements, but a very low alkalinity.