There are many brands out there. Many people have their preference. Mine is Instant Ocean. Relatively inexpensive, and mixes closest to the parameters I keep in my tank.
Ask 50 people and you will probably get 20 different answers. So far I have had good results with Fritz and that’s what my favorite LFS swears by and uses. Just gotta find what one you like and one that has Params that you like.
I like red sea in the blue bucket. It mixes very close to what I keep my tank at. What do you keep yours at? That might be a good start and help point you in the right direction.