Valentini puffer (Toby) have great little characters! If you are willing and have a source to keep buying rivershrimp every week then wartskin anglers and zebra, fuzzy dwarf and fumanchu lionfish are cute.
IMO triggers will wreak havoc and get way too big for that tank, same for tangs.
There are some gorgeous wrasse species out there and very tolerant of each other. I'm loving the leopard wrasse and the lunar wrasse at the moment.. And a nice sifting goby like a pink spot goby or a blue cheek goby.