My two-pennorth, for what it is worth and I am only ever a solo rider who never listens to music or radio, bike or car.
Wired Autocom...
Simplest of all intercomms I have used, plug in, turn on, forget.
Brilliant reliability, functionality and performance.
A little wind noise in the helmet causes the Autocom to transmit noise.
Excellent customer service (used to be...)
However...
When cables and connectors go bad they can cost more to replace than a new unit.
I have lost count of the number of times I have had to stop a mile after a fuel stop to reconnect my intercom cable.
Sena 20S...
Brilliant range, much, much greater than Autocom.
No bloody cables to trip over.
You can't forget to reconnect after a fuel stop etc. etc.
Many more features than old wired Autocom.
Instructions for use are 'odd' - does 'Tap the jog dial' mean just tap it or are you supposed to press it till the switch operates? I can ride along tapping my horn button all day long but the horn never sounds...unless I 'Press' it.
App connectivity for set up.
A little wind noise in the helmet causes the Sena to keep yapping 'Say a commaaaand' into your ear, but it does take a lot more noise to trigger.
Like Rae, great volume with either ear buds or in-helmet speakers.
However...
Change your helmet, you have to change the fitment.
Have more than one helmet, you need more than one fitment (not including the clip-on head unit).
Can be fiendishly tricky to fit to modern helmets with neck skirts etc.
Can be pernickety when it comes to how and in which sequence you connect your devices.
Way too many 'features' which no-one can fully understand.
Also, and this may just be 'me'...
I find the unit VERY difficult to operate with even summer gloves on and the finger contortions to access phone, ambient noise feature and even volume, to be almost beyond my physical ability.
There are two possible reasons for this...
Firstly I could just be a klutz (OK, three reasons). I am more dextrous than most so don't think it is this.
The mounting position on the Schuberth C3 is a long way to the rear (to clear the chin-bar and visor mechanism) and this makes for a 'weird' arm position trying to get to the controls. It's easy with no jacket on but the normal restrictions of heavy/bulky clothing make this arm bend very awkward for me but I could just have weird arms.
I just don't do the miles with other users to ever get the muscle memory locked-in. I don't even know how to connect to another user. I mean, it's not rocket science and every time I read the manual it's like 'OK, easy!'. Then the next time, a few months later, I can't remember.
In summary, the performance of the Sena is way better than any wired Autocom I have ever experienced.
In their defence, Autocoms are simple tools which you fit and forget whereas the Sena is way too complex for almost every user's needs. The controls remind me of the left handlebar of an R1200GS or K1600...cluttered!