Where are you travelling??
The London mainline trains on Southern are considerably roomier than the FCC heaps.
There are two configurations. The 3+2 across seats (too cramped) and the 2+2 (comfortable). But in both cases the distance between the facing seats is greater than on FCC trains where...
So the other people will generally be quiet and considerate, and you can always take a walk to the bar carriage where you'll be offered a selection of decent quality cold beers served in an actual glass by a smiling barman