Fossils are more likely to be found in sedimentary rock and here are the reasons why.
Contrary to igneous and metamorphic rocks, sedimentary rocks do not change. Their name itself indicates that they pretty much have remained in the same place and state for centuries.
In the same line of thought, igneous rocks often are remains of volcanic eruptions or have been transformed by heart and erosion. Metamorphic rocks are like igneous rocks in that they have mixed with other rocks, have been crushed and mixed and also have been affected by extreme temperatures.
Therefore sedimentary rocks, either because of their location and the fact that they do not come from any volcanic activity, are more likely to remain the same and therefore whatever fossil that will be imprinted in it will undoubtedly do it easier in such a type of unchanging rock.