As Brian points out, the hoods are designed for the lenses that you have. There is a reason that they are the shape they are: They do the best job keeping unwanted light from ruining your shot. If you look at petal shaped hoods, they are very different from one another based on the characteristics of the lens they are mounted on.
Use the hoods that came with your lenses and concentrate on getting the best image possible. That will make you a professional sooner that the look of your equipment.
The only time you may want to use a different hood is when shooting at an aquarium or zoo when you want to use a rubber hood pressed against the glass to minimize reflections and stray light.