Depends on what you are wanting to spend.
Shipping costs make it tough to beat a LFS on lower cost items, but if you have the means you can get some really nice stuff from reputable online vendors.
There are several good online suppliers including (in no particular order) WWC, SC, JKR, UC, ASD, CC.
I would just browse the sponsor threads and find one you like.
Ok, thank you both! :) I have bought some coral frags from my lfs and I am running out of room, so I want to get like 4 more really elegant corals. I was kind of wanting to get some bright color zoas, 1 acan, and I don't know what else. Is there a certain amount of corals I can have in a biocube 14? I have 19 small coral frags now.