I use them all...
Real - Best looking and safest for fish but have a lot of upkeep
Plastic - If you buy good ones, they are fine for your fish, and often look just as nice as real ones. But they dont "flow" like real or silk ones do. They are also easier to clean than silk since they dont hold the funk.
Silk - Looks nice, "flows" like real plants, and has nice patterns. They are also very easy on the fish. On the downside, they really only come in plant forms that have large main leaves (like swords and anubias) I dont think I have found slik plants that look like grasses or other plants with small leaves.