My go-to online vendor for general fish is LA. For more specialized fish, I go to PacificIslandAquatics, AmongtheReef, and Aquatic Collection.
As much I like to support the local lfs, it has been pretty depressing every time I walked into the store lately. I always look forward to do my weekly LFS tour in NH two years ago when I can take the drive and go to 4 different stores. Even if one didn't have good stock, the next one may have something special. Now, there's only one and that is Jays. I always like to go there and still do. But recently, their stock is very average with close to nothing special. I don't know, maybe it's the day I go(Friday) but I thought they get their stock on Thursday night. What's even more disappointing is that you want something, he tells you to call on Tuesday when he does the ordering. You call him on Tuesday and tell him what you want. He'll say he'll put it in the order but call back Thursday night to see if what you're looking for has arrived. You call Thursday night to find out it's not in the order received. He asked you to call him again on Tuesday and the cycle continues. I did this for two weeks without any success. What I was looking for was nothing extremely rare either. One occasion was Blue Reeef Chromis and the other was Sunburst Anthias. I got fed up and ordered them from LA and they showed up in my doorstep the next day. Despite all this, I still take the drive there almost every week. But after 5minutes into the store, I felt the remorse of driving all the way there.
If you want something more rare, angelfish like Conspicuous, Personatus, Iterrupta angelfish. Rare tang, and wrassses, consult the above online vendors.