It depends on your budget~ but fairy and flasher wrasses are awesome and can be kept in pairs.
If you want a hunter, get a nice male melanurus wrasse. Good fish, I have one in my reef. He is always on the lookout. Not sure how your sixline would take to him though as they have stripes like the sixline. Much prettier IMO though.
For gorgeous fish look at Rhomboids{extremely pricy}, Hawaiian flame, pink margin, Roseafascia,yellow sided, Australian Scott's, Labouti,Lineatus,Pylie..gosh they are so many nice ones.
Flasher's are great too, I like the McCosker's, but there are some more rare and of course pricier..if you look and shop carefully. There are some awesome threads on this forum by a gentleman that specializes in fairy and flasher wrasses. His name escapes me, but someone will know. He has fabulous photos of them. Good luck!