Part of it depends on what you want to hook up, or if you just need intercom. Whether you want wired or wireless is also a consideration. We like wired, and use the Starcom1 for our rides.
The wife and I use this one also and works great with no problems!:2thumbs:My wife and I like the Cardo Q2. Were very happy. When she calls me the first thing she ask, is were are you. When I tell her I'm on the hwy she is all ways amazed how clear and quite the the Q2 is. When your next to each other it like your sitting still having a conversation at your dining room table. Just my 2 cents. Here is their web site, http://www.cardosystems.com/us/scala-rider/scala-rider-q2-multiset
Good luck.
If you want to really get confused, spend some time going over the information offered here: http://www.webbikeworld.com/motorcycle-intercoms/
I have the G4 and the reason is; a lot of riders seem to have Cardo Scala systems and the G4 is backward compatible with them. So not only do I have a way to talk to my pillion(wife) but I can also communicate with other riders using Cardo systems products.
G4 system for me. I have the Q2 on some other helmets but the newer G4 was a great upgrade.
The Scala G4 is the new and improved version of the Q2. I sell Chatterbox and J&M also but, we use the new Scala G4. It seems to be the best price point and is the easiest to use IMO.
As posted earlier, I have the G4. However, if I were to do it again, I would look very hard at the Sena SH10. In the analysis Web Bike World did, this came out on top. Yes, the G4 was included in that review.