I use Lutron RadioRA for my lighting system. It works flawless, although it is more expensive than X10 or Insteon and it is only lighting. There is no other home automation involved. I have it all connected with an MX-3000 and an MX-980, as well as the base remotes that come with the Lutron package. Almost all lights in my house are on the system and since I have a few remotes hooked up to the system, I can adjust the lights no matter where I am in the house.
A friend of mine has a few X10 dimmers/switches and he has nothing but problems with it. It works maybe 1/3 of the time as intended. I know there are some on these boards who have had flawless or near flawless setups. I believe the house in question here has goofy electrical problems which constantly interrupt the X10 signals. I guess mileage may vary with X10.
Insteon is supposed to be the next generation of X10, or at least that is what it is compared to. You should go to the forums at
www.smarthome.com for more details about Insteon and post questions there.