Here is what I can tell you.
Elan doesn't make any lighting control at all. They make whole house audio and video products, serial controllers and touchscreesn/keypads. They can do some limited control of third party lighting, including Lutron Homeworks and Vantage. Possibly Centralite too, I can't remember.
I can't speak to Insteon or the Z products (z-wave, zigbee) never used them. AFAIK
, Insteon is a powerline carrier product like X10 and UPB. Not saying it is"like" x10, just that it is a powerline technology. UPB is an extension of x10 that is supposed to be more reliable and I have heard that it is. No personal experience. X10 is crap. From personal experience.
Lutron has two different systems (really three) Homeworks, which is a professional level ( and dealer only) lighting control system. It comes in two flavors, hard wired and wireless. The hardwired system, along with, IMO, Vantage are the top two central lighting control systems. They are also the ,most expensive. They are typically specced in new construction because they have a completely different wiring topology than a standard house. All lighting loads are home run to the dimmer panels that can be located throughout the house. There are no switch legs. The regular toggle light switches do not exist in these systems. They are replaced by keypads that are hardwired back to the controller. Any button on any keypad can control any load or scene in the home. Vantage takes their system further in that in can be a home automation controller as well and they now offer whole house audio products.
Lutron Homeworks wireless is, again, a professional level controller based lighting system. It is designed for retrofit situations. Each standard toggle swich is replaced by a Homeworks dimmer. Each dimmer communicates with a central controller. The controller acts just like the controller in the wired Homeworks system. Homeworks wired and wireless systems can be intermixed.
Radio Ra is an entry level system limited to 32 devices, dimmers and keypads. Each Ra dimmer replaces a standard toggle switch. Scenes can be programmed etc. It is pretty simple and pretty basic. It is probably available to a DIY. Homeworks isn't. By using a Chronos bridge, you can double the capacity to 64 devices. Once you do this, the price differential between Ra and Homeworks becomes very small. (equipment costs. there is still the cost of installation and programming with homeworks)
I don't know who offered an RF solution first, but Vantage Radio link has been available for quite a few years and may have been before the Lutron solution. Vantage has two systems as well. (not really two separate systems, they can be intermixed) the hardwired Infusion system and RadioLink. The Infusion system works like Homeworks. Each load is home run back to the dimmer panels, there are no switch legs. Each keypad controls whateve load or loads are programmed into it.
Radiolink is similar to Hoemworks wireless. Each standard toggle switch is replaced by a Radiolink dimmer. The main difference is that in Radiolink, the dimmer is really two devices in one. The dimmer is the dimmer and the faceplate/keypad is a separate control device. Each button on the radiolink dimmer can control any load or scene, just like the hardwired system. There is virtually no limit to the number of devices you can use and the processor can be a full control system too. The only real difference between the hardwired and wradiolink is aesthetically. You will still have a bank of switches to replace and they will still be there. Hardwired eliminates much of the wall acne. For new construction, it is a no brainer to use a hardwired central system. For major remodel it could be cost effective and worthwhile too. For a retro situation, Radiolink works great.
Lutron and Vantage are by far the costliest of all the solutions you mentioned. An apples to apples Vantage to Lutron should be about the same.
Ra would be next least expensive. The rest are really pretty cheap. Ra dimmers list for somewwhere around $250. Homeworks and Vantage are a little more depending on config. Control 4 dimmers are a hundred bucks. UPB are maybe 80 or 100. Insteon are only about 40 bucks.
:utron Homeworks and Vantage are pretty much bulletproof and 100% reliable. Ra is very good. I really can't say what the others are. I do know that X10, in my experience is very unreliable.
Hope that answers some questions. Feel free to post more specific questions.