The honey gourami is a top dweller, you've got neons for the middle, so a bottom dweller would be a good idea.
Catfish are the obvious candidate, but you need to ensure that you don't overstock too much. If you wanted to take Munroco's suggestion, it would be easy to do so, as cories need to be in a group of at least 6, and I would be uncomfortable with 6 of the larger species in your tank. Panda cories would be OK, they being a smaller size, and definitely fine would be the dwarf species, c.habrosus and c.hastatus. My personal favourite are the habrosus, often called Salt & Pepper Cories in the shops.
An alternative would be 3 or 4 bristlenose plecs
If you didn't fancy a catfish, then 4 peacock gudgeon would be superb, if you got 2 males and 2 females, and give them some caves, you might find them breeding.