I would stick with the livebearers, guppies, mollies, swordfish, etc. I had guppies and they bred great without much help. You just had to provide places for the babies to hide, or have a nursery tank, that way you could take your pregnant females out and then the babies would be safe from all the other fish but their moms.
Babies will get sucked up into the filter, so beware.
Betas are fun, but they require a lot of "extra". You have to keep the males and females seperate until "just" the right time. Females can be kept with females, but males MUST be kept seperate from males or females. Therefor you must have plenty of extra tanks to keep the males seperate. Even if you keep the males seperated into jars(like many breeders do) you still have to clean 1/3 the water out weekly or every other week. A bit too much work for me. LOL
Guppies(and other livebearers) can be kept in a communal tank. Multiple males and females together without a lot of aggression.
-Kim