Which Groupset?

Seen plenty with the 10 speed due to accelerated wear and tear (poor maintenance and the like).

Isn't 8/9 speed chains are generally stronger than the 10/11 speeds one?

I work in a bicycle shop 20 miles outside London, we don't stock 11 speeds or Campagnolo (oddly enough have some belt drive component), it can only be ordered in from the distributor.

You are introducing a new element here- that of "what groupset will put up with shitty maintenance for longest without breaking"