For me it's primarily 2+1 seating (or more specifically the 1 side, though even the 2 side will be better than Standard as it's wider). I also voted "tea, coffee etc" because the cost of providing it is negligible (a very large number of employers provide it too).
The price I am willing to pay is about 160% of the Standard fare applicable to that train, with the same restrictions. That is in line with First Class fares across Europe. Not, with only very few exceptions, more than that.
For food I would rather be able to order a la carte and pay as per what I order, though it's nice to have it served on proper crockery etc as part of the service. This is what DB do, for what it's worth. I don't want to be paying extra for "freebies". In some cases, e.g. a long distance XC journey or one down to the Westcountry taking in a mealtime I would happily pay well over the odds for a nice 2-course meal, but sometimes I prefer to just take my own.
I will not upgrade to First Class if the seating is 2+2, and I resent having to upgrade to get a seat because inadequate capacity is provided (yes, you, pre-80x TPE), it is supposed to be a free choice to upgrade to a higher quality environment.
I don't agree with the provision of First Class on overcrowded commuter services. It would be better to abolish it and have that space to allow everyone to spread out, as Chiltern mostly did years ago, and Greater Anglia now have.