40B Stocking List?

[Enigma]

I'm trying to work out my stocking list for my 40B (+15g in sump) I have fish that I may not keep, and I may like some different fish.

Have and keeping:
1 - Juvenile False Perc (standard Nemo)
1 - Adult False Perc (black)
1 - Signal Goby

Have and not too sure about keeping:
3 - Juvenile Green Chromis
2 - Adult Bangaii Cardinals (I think they're adults, appear to be male and female)

All of my fish are presently in the QT/HT, being undergoing PraziPro and Paragaurd treatments.

The chromis . . . they're just not that interesting. I'm very surprised to still have all three. I figured they'd kill each other off. If they didn't kill each other off, I figured I'd kill 'em in a week. Didn't happen. They look amazing after the PraziPro, but they're still pretty boring. I never planned on having them long term.

The Bangaii cardinals are new additions. I purchased them on Friday. I'm not sure about them. They eat, but they don't do much. They are interesting looking, but they're boring. Everyone seems to like them, except me.

Don't have and want:
1 - Blue Mandarin Goby (if tank/refugium conditions allow, or ORA)

Don't have and kinda want:
1 or 2 - Purple Firefish

They all get along very well in the QT (33 gallon with lots of PVC), but the Bangaiis do make my Signal goby a little nervous.

Anyone have any suggestions as to my best course of action? I'm so undecided.