There are many different species of Rudbeckia that are grown for the garden. The most common is Rudbeckia fulgida, the perennial black-eyed susan. These are sometimes nice in the garden but I think they're a little, well, vulgar so I never user them in bouquets.
The one I do use is Rudbeckia hirta, a short-lived perennial in Michgan that is usually grown as an annual. Rudbeckia hirta has been selected into a dozen or more strains for the garden and cut flowers, and some of them are really quite nice. They come in singles and doubles with brown and green centers. Many are golden yellow but others are burnt orange or mahogony or blends of all of these. I really like a variety called "Chim Chiminee" that has quilled petals.*
The best picture I have shows a mahogony double and some bi-color red and yellow singles. I like Rudbeckia hirta because of the different flower forms and the rich colors. Some of the doubles can be quite striking but for the most part they are not flowers you sit and stare at in awe. They are nice "supporting players", providing notes of contrasting color.
Rudbeckia hirta don't usually rebloom much but they can be succession sown. I started my first set today and am growing "Cherokee Sunset", "Goldilocks" and "Maya" (all doubles) and "Prarie Sun", a huge golden yellow single with a ligher yellow center. I'll try to post some pictures of these varieties later this summer.
*I don't know who cooks up the names for these flowers. This one originates from Thompson and Morgan. A friend of mine liked the pictures of "Chim Chiminee" in the catalog but refused to buy it because the name offended her!