Welcome to the forums
Sounds like a lovely tank thats starting off pretty well! Unfortunatly (as you probably realise) the fish you like will not all go together. Most cichlids do not go with the other fish you mentioned, danios do not go with bettas and more
For a 150L (40G US), I'd go for
6 Corydoras (whatever sort you like, preferable 1 sort or 2 times 3)
a shoal of harlequins (around 7)
a shoal of cardinals (around 7)
some guppies (2f on every m, about 6 in total I think)
1 bristlenose plec
Or you could not get guppies and get a shoal of zebra danios (around 6). I'd definatly not get less than 6 zebra danios though, and not get them when you get guppies seeing as they might be nippy toward the males tail.
perhaps a banjo catfish as well, seeing as my cousins absolutely love my banjos ... but that would be pushing your limit
It will have colour, quite a lot of stuff going around (Specially with the cories) and be a lovely tank if you ask me
You could also concider rummy nose tetras, always a lovely addition to a community tank
Good luck setting up the tank!
--Edit--
Thought I'd let you know what I used to have in my 40G

(Its changed with births, deaths, bigger tanks etc

)
8 zebra danios
5 cardinals
5 ember tetras
5 black neons
3 peppered corydoras