I have a Lynx, I picked it over the Nanocom primarily because it's cheaper and I'm not really going to use it much.
Lynx uses a laptop, Nanocom is a standalone portable device.
Nanocom has more features than the Lynx but the features that Lynx has is good enough for me anyway.
Lynx coverage list
One thing that is better on the Lynx is that it will work on any P38. If you get a Nanocom for a diesel it won't connect to a petrol P38s engine ECU (but it will connect to non specific things such as BECM, HEVAC etc). I guess it isn't that important though unless your planning to be helping mates all the time. You can also buy more extra cars for the Lynx such as (D2,L322,Sport,Defender and more) where as the Nanocom only seems to cover P38,D2,Defender