From everything I have read and understand, I don't think you can declare one salt the best. There are some salts that may have more stringent QC controls, research and testing and will be more consistent and reliable, but they come at a price as you are paying for that sort of research. However, I think there are many variables to consider in terms of salt.
1. Availability: It is typically better to have salt that is available at your LFS so you can get it in a pinch
2. Parameters: What corals will you be keeping? Where do you want to maintain your parameters? Know what you want to keep and getting salt that closely matches your parameters will keep it more stable. However, if you have a larger tank, it may be less important as a small water change will not drastically impact the stability. For smaller tanks, probably helpful to keep it as close as possible.
3. Price: If you have a large tank, price may be a big factor as costs can add up. Larger tanks can also handle slight changes better than a small tank. If you have a smaller tank, impact on cost of salt isn't as drastic as a full bucket would last you a long time
4. Convenience: How are you storing your salt water? If you have room for a saltwater station to store and mix salt water, then having salt that takes longer to mix is no big deal. If you don't have room and will need to mix salt as needed, how quickly it dissolves could be more important. You can still leave the buckets out for mixing overnight but depending on your lifestyle, speed of mixing may play a factor
5. Reliability: There are some brands that have stringent quality control so you know that what is advertised is what you get. This is probably closest related to price. You pay for some extra assurance. Doesn't mean there aren't bad batches but it is your responsibility to test a new batch/bucket.
6. Cleanliness: Some people prefer no residue, some don't care. Your choice based on factors above
More importantly there is husbandry of your tank that also determines the success of your tank, not salt alone. Is there a best salt? Probably not. However, is there a salt that is best for you based on what is readily available and based on what your tank needs and what is important to you? Probably yes.