As long as you have lots of pods mandarin fish are cool. Really colorful and passive fish. Too many die because of a lack of pods and some won't take frozen foods.
if we're talking about sushi, nothing beats wahoo best fish hands down
if we're talking about fish for the aquaria id say a group of anthias, lots of color and lots of movement
or a pair of something like bellus angels my favorite angels
The mandarin (if you have a large tank) is by far the most colorful fish, after that i believe its the Hawaiian cleaner wrasse. Next up would be a toss up between the potters angel and the 6 line wrasse. all of these fish are inexpensive an reef safe.
Marine Betta I love mine. As long as you dont have any really small fish its 100% reefsafe. It is a little shy at first but when its on display its presence dominates that part of the tank.
Fu man chu Lion - Same as above
Mystery Wrasse - Awesome wrasse needs no sandbed, sriking colors.
Love my Achilles Tang....eats right out of my hand...gotta love that....also looking for a Red Sea Sohol Tang to add to the tank....can't find one big enough at the LFS.
I would say my favorite has been a French Angel. They are beautiful and have great personalities, a lot like puppy dogs. But not really reef safe.
Also, I am currently very attached to my Moorish Idol which is beautiful and also has a great personality but is not reef-safe either.
My favorite reef-safe fish is probably a Naso tang (I prefer the black over the blonde). Beautiful fish when adult especially with streamers, and mild-mannered for a tang.
I also like royal grammas. Colorful, inexpensive, reef-safe, plays well with others, and is easily obtained, yet entertaining and always appears a little grumpy.
My mandy is my fav fish. Shes my fav because shes the most difficult fish in my tank. shes also the prettiest fish in my tank, and the shyest too. See... marvel in her beauty.