Both my bikes have a 105 R7000 setup, the Trek came with Tiagra and I upgraded in part because I had some of the components lying around from the Racelight build (notably the shifters - I had cable brakes to start but swapped to Hydraulics) and because it made sense to have exactly the same drivetrain on both so I needed to keep fewer spares on hand.
In terms of shifting performance I've found that no matter what drivetrain you use provided it is well setup and the cables in good condition shifts equally well. The new Shimano stuff definitely has a lighter feeling action and to my big fat hands the hydraulic levers being bigger feels better, but once the click happens, I don't notice any difference.
My old commuter had R3000 Sora on it and I did over 20k miles on it without feeling like it was inferior to the better equipped bikes I've ridden.
Overall I think that for Shimano, Tiagra is in the sweet spot of price/performance/durability but Sora is pretty close.
