I'm looking into reducing my camera weight and the cost of adding new lenses (yes, again) with a bit of GAS added as usual

So my Canon gear is off to a dealer.
My short list includes the A7C II /A7CR. There is around £500 difference in price between these two or greater if I don't go full frame and opt for the A6700.
I need to add a minimum of one lens too. The lens options I'm considering is at the top price point the FE 24-70mm 2.8 GMII or for a lot less the Sigma or Tamron 2.8 equivalents.
My concern regarding choice is less financial (saving would be good!) but more about sharpness.
Any thoughts on the three lenses regarding sharpness from real world use?
I also intend visiting WEX to be sure the viewfinder is acceptable in use as I wear glasses and struggle a little with some EVF's.