I would strongly reccomend pearls (though, like most gouramies, they hate mollies - they won't attack them though). These are my favourite gourami species (and my favourite fish in general actually). I've been breeding them for years and have only ever had one aggressive one. They are very social, will 'school' if in larger groups and males look stunning - females have a more subtle beauty. They appreciate tall and floating plants and a group of 3 (say a male and 2 females or 3 females) would be fine but you'll get the most out of them if they are in an even bigger group. Just make sure the females outnumber the males (though, actually, these are less likely to fight than other species).
Other options would be the banded gourami (Colisa fasciata) which are much like pearls character-wise but look more like dwarfs. They are wonderful fish, surprisingly active and not as shy as other species. Again, a group of 3 females is fine but any group with 2 or mroe females per male works equally well. Another upside is that they are not quite as inclined as pearls to spend time near the surface - so the danios won't get in their way. Females are almost as colorful as males.
A similar species is the thick-lipped gourami - Colisa labiosa. Whereas both afformentioned species grow to about 4" (a little larger for male pearls), this one gets to about 3.5". They are pretty much identical to bandeds in terms of requirements but, IME, not quite as active. There are a couple of color morphs available to choose from (and you cna mix them).
A larger species is the moonlight gourami - Trichogaster microlepis. These are silver in coloration but, in the right light, appear almost violet in color which contrasts beautifuly with their orange-red (in males) or yellow (in females) ventral (feeler-like) fins. These are much like pearls in character but more boisterous. Juveniles are trickier to sex but the ratio doesn't matter too much if you keep a group. Their major disadvantage is that they grow to 7". Having not been bred extensively, they are very hardy fish.
If you are not necessarily after something large, honey gouramies are also great (about 1.5"). They are very similar to dwarf gouramies (and indeed can hybridize with them) but are considerably hardier and, IME, more active. There are several color morphs but the wild type, IMO, is the most beautiful with pale cream-colored females with a single dark horizontal stripe running from eye to caudal peduncle. Juvenile males also look like this but adult wild-type males develop a rich honey-yellow coloration and, when in breeding condition, a dark blue-black ventral coloration. They are very eye-catching dispite their size. Males are quite territorial but would be happy together if 2 or so females are included per fish. In your size tank, even a males-only group should be fine as they'll set up territories and then pretty much ignore each other except for the occasional display. These are not really social gouramies - though the females can be.
If you are not after 'conventional' gouramies, croaking or sparkling gouramies might also be a consideration and there are some rarer options too - but I suspect this isn't what you're interested in.