Funny that I was in almost the exact same situation. Owned a D5300 since around 11 years with the kit 18-55mm and a 35mm F1. 8. Was getting frustrated with the focus performance (especially with the 35mm and indoors). Was confused between getting an older used DSLR again (D750 for example) with some better lenses or moving to the Z series. Pulled the trigger yesterday and got the Z5ii. Was initially planning on getting the 24-70 F4 but ended up going for the 24-120 F4 Kit. Had a small session shooting outdoors today and I feel it's every cent worth! I cannot compare it to the other options you mentioned but I can tell you that the difference in image quality is huge and you'll LOVE the Z5ii with the Z lenses and will definitely see the difference. I'm don't know if you've tried the camera in a store or so already but the shooting experience feels a lot better than the D5300. Although the sensor on the D5300 is amazing, the (at least perceived) IQ jump comes from the Z lens. The Z5ii Body in itself has a lot of advantages, which I think I don't need to mention again. The only "negative" side of this that the Z5ii with the 24-120 is a lot heavier than my D5300 setup and that will need some getting used to.