Image quality from apcs setups are very close to FF these days. Personally, my favourite focal lengths are 24mm and 40mm. The nikon 24 1.8 goes for 80k while the sigma 16mm goes for 30K. It's hard to justify the extra cost imo. That said the 24-70 f4 is the best travel lens on the market and it's all you'll really need, so you cant go wrong with it.
Both are great options