After I bought the Sigma 150-600 sport, I felt the same way when the Nikkor came out. Actually, all three are tremendous zooms for the price, then or now!
This might not be the perfect spot to bring this up (it might though)..... I have a D500 and recently bought the Tamron 150-600G2. Although I take pretty good pictures with it, I have significant issues with the "combo". Today I was taking pictures of wildlife at a local site well-known for the diversity in wildlife. The lens/camera refused to focus on a regular base. This could typically be fixed by re-seating the lens on the body (i.e. push the unlock button, move a little back and forth, and relock). What to do? Will sending the lens back fix anything? Is is a camera issue? Would replacement with the Nikkor 200-500 be the best option? That being said, I did have the Nikkor lens for a day or two and did not like the feel at all and send it back..... regrets? perhaps!!