Here's a few considerations that might help you decide. Generally, all salt mixes will do fine with most reef animals, presuming the aquarist is aware of the impact of alkalinity, calcium, magnesium, etc... Where the salt mixes differ is 1) expense, 2) insoluble "other stuff", 3) levels of minor elements (Ca, Alk, Mg). The expense aspect isn't quite as straightforward as one might imagine, as the number of gallons that a given box/bucket will mix to may not all use the same base specific gravity (1.026). Bulk Reef Supply has a video on their site that examines this issue, with some salts actually working out to be cheaper per gallon even though the box/bucket price is higher because it will make more ASW than others.
Insoluble "other stuff" is going to vary from brand to brand. In my experience, IO "regular" probably has the most insoluble "other stuff" when freshly mixed. Nevertheless, the amount of stuff is relatively minor, and I used it for many years - I just had to empty the mix can and clean it out on occasion. "Premium" salt mixes generally have a lot less of the "other stuff", and tend to mix up clear very rapidly.
The last consideration is probably the most important. There's a wide variation in the alkalinity of various salt mixes in particular, and depending on how you use it, that might be important. For example, someone that makes only relatively small weekly water changes might appreciate a relatively high alkalinity mix like IO, Reef Crystals, or Red Sea Coral Pro, since an equivalent amount of these will raise the alkalinity of the tank water more so than will a low alkalinity mix like Tropic Marin Pro Reef (alk ~ 7). On the other hand, someone that's managing their tank's nutrient levels with relatively large water changes of 20%, 30%, or even 100% such as the "weekly water replacement" method for pico tanks might want their new water to be an exact match to the alkalinity/Ca that they run their tank at. One can, of course, adjust new seawater to be an exact match for alkalinity by either adding a carbonate supplement to boost it or adding hydrochloric acid to reduce it, but having to adjust the mixture each time is a bit of a PITA. So buying a mix that's a lot closer to their tank's typical parameters makes sense.
if you start getting more into LPS and SPS IO Reef Crystal's would be a good choice. Or the blue bucket red sea salt. I personally use Fritz Reef Pro Mix, but my tank is SPS dominant 
