Partially Re-stocking A 54l 60x30 Tank

I echo Sue's comments on the harlequin rasboras. My PH is similar to yours, even slightly higher at times. Of the 3 shoals of tropicals I've had, the harlequins have done the best - all 6 are aged 3+ and still looking as healthy as when I bought them (touchwood!).

Thanks @Helen, that sounds like it's turning me off of the Cherry Barbs. I've got shrimp and Corys, so there's plenty going on in the bottom of the tank, I'd rather have fish at the top.

When I was playing around with the CC last night, I don't think it distinguished between the Harlequins and the Espeis, despite the Espei being called a "Slender" Rasbora on some sites.

So I'm down to three - Espeis, Threadfins and more Honey Gouramis. I honestly didn't check the gender of the Threadfins (or anything else, bar noseying at the Bettas), so this is something to consider.

Perhaps it's because I'm still a bit naive towards fishkeeping, but the Gouramis feel like the safe/boring/practical option and I can't help wanting something a bit different/fancier. The Threadfins certainly fit that bill.

Whilst I know LittleFish has endorsed getting more Gouramis, it doesn't seem like there's an inherently "best" answer here from the other comments. I'm planning to go back out over the weekend to pick up some new friends, so I think I'll take a look at what's there on the day (now that I've done some research and thinned out my list) and go with whichever of the three grabs me the most.

Thanks for all of your input, though. After my various misadventures, it feels good to be going about it in the right way..

There are two tropical fish shops about 25 and 30 minutes away from me now. Both have good stocks of fish, one is slightly cheaper, but has very little except fish (hardly any tanks, decor, food etc.) and the other's got everything, including turtles, axolotls, koi carp, water features and the rest, but costs a bit more.

So I went to the more expensive one first, because they carried all three of the threadfins, rasbors and gouramis, while the other didn't carry threadfins. I also wanted to get a "cave" for Princeton and some more decor in general, as I stole from the main tank to set up his 25l last week. So I've got a few more moss balls, split between the two tanks, some silks and a cave for Princeton, another silk and some more java fern on a piece of bogwood for the main tank. I can't grow plants for the life of me, and I've killed all the "easy" floating plants I've tried too, but I did buy java fern on a piece of driftwood before that's survived in my main tank, despite my best efforts, so I figured I'd try another piece.

Looking around, I wasn't taken by the rasboras on second look, and they had no threadfins left. This is actually the same shop my two current gourami came from, so I picked up four females (two yellow, two red) along with the non-fish.

They had no Japonica shrimp today, just crystal red,so then I stopped at the other shop on the way home and picked up four more there. Oddly enough, this shop didn't have any coloured gourami in today, just the natural ones, and most of them looked to be male. Had I come to this place first and called it a day, I would have ended up with the espeis instead...

Everyone's been acclimatised throughout the afternoon and it's bloodworms for tea!

Congratulations on your new arrivals.
I hope that they have settled into their tank and have enjoyed their tea.