Step 1) Figure out what Alk, Cal, and Mag numbers you want
Step 2) Choose salt based on that
Plenty of people use all of the salts on the market, barring a few recalls/replacements from companies in recent history, it all really depends on what you want to get out of it and what your goals are. For instance, if you don't plan on having corals, you can run several salts on the cheaper end with no worry. If you plan on having a tank packed full of coral, you may want to shop as I have mentioned in step 1, as it will save you money dosing your way up to the numbers you want.
Personally, because I am lazy and impatient, I use the ESV B-Ionic seawater system. Per the normal instructions, it gives me a dKH of 9. Previously I was using TMPro which only gave me a dKH of ~7-7.5. Instead of dosing my way up to 9 every time I do a water change, I decided it was more manageable, and more cost-effective, to spend the extra $20 on the ESV. Plus it mixes ultra-fast and doesn't leave residue behind (I'm lazy and don't like to clean buckets.) That's MY reasoning for using what I am using. Your reasoning may be completely different.