As everyone is saying the easiest is guppies. You dont seem to like that option. What others are saying is if its just for what you are saying its for you are wasting your time and money. Like I said if its a side project then great. You will not get a huge breeding group out of a 10g. It wont happen fast unless you pick already pregnant guppies. Then you will need to seperate the babies from the adults or the adults will eat them. If you can find pregnant females you wont need males for them ever again if the water and tank conditions are right they will be pregnant about once a month from now till they die. They store sperm. Pit some breeding mops in the tank or guppy grass or other long leafy stem plant for coverage.
If you are looking for larger or faster breeders I don't think its a viable option for what you have planned.
Danios dont breed half as easy or as fast as guppies.
My lfs has a breeding pair of jds right now that they cant get to stop breeding 150 for the pair. Youd need a 75 min to make them happy though. Those babies are an inch + in a month.