One last bit of advice from my own experience, then I'll let you digest in peace.

Think about what's most important to you in a fish you're planning to keep: interesting behavior? Uniqueness? Lots of activity? Beauty and a peaceful disposition? Those can all make a difference. For example, I'm drawn to Banggai and threadfin cardinals because of their beauty and because I like planning biotope aquariums for them, but I've come to the conclusion that they're a little boring as the only fish in the tank, just because they don't do much except hover in place.
On the other hand, my new dottyback is more entertaining to watch (even though she spends a lot of time in the rocks) because she's so active. From the moment the actinics come on until the lights go out, she's busy, busy, busy, darting in and out of the rockwork and coming out to investigate her surroundings. However, her territorial nature means that I probably won't be able to add any new fish now that she's established herself in the tank.
And finally, a dwarf moray eel (which I also briefly considered, but decided against because (a) he was too expensive, (b) my tank is open and he would crawl out, and (c) he really wouldn't do much besides hang out in the LR and eat) appealed to me just because it would have been so different. But again, not terribly interesting behavior, for the most part.
I chose a dottyback, even though they can be feisty, because I figured that I was limited to just a few fish in such a small tank, so I wanted to make them "count", in terms of being both beautiful and interesting to watch. However, everyone's idea of what's most important in a tank inhabitant is unique. Try to figure out what's important to you in a fish, and then which species both possess those important qualities and will work well (in terms of adult size, needs, behavior, etc) in your setup. Good luck! :thumbsup: