I would recommend japanese quails.
Here are a few reasons why.
1. They're good layers and their eggs are a decent size (compared to tiny king quail eggs. I eat their eggs too, but most people consider them too small). It takes roughly four eggs to equal the size of a chicken.
2. They're one of the most common species, so it should be pretty easy for you to find a breeder.
3. They can be used for meat. I don't use mine for meat, but plenty of people do. I don't know if you wanted them for meat or not.
4. They make good pets. They're less skittish than most other species, and they can be tamed without too much trouble. They're a decent size to have as a pet (whereas king quails are way smaller).
5. They come in a wide range of colours.
This would be my first suggestion, but it really depends on what you want them for (meat, eggs, pets...). I have owned four different species, and I think they're good for different reasons. For example, king quails and california quails are generally ornamental birds, but japanese and bobwhites are commonly used for meat and eggs.
In the end, it's up to you. If you have any more questions about choosing the species, or anything else quail related, feel free to ask. Hope this helps