If you're aiming for 4K performance without going bonkers draining your bank account, the GeForce RTX 2070 Super is the best graphics card option. Performance is close to the 2080, but at a more palatable price. Even better, Gigabyte's factory overclocked Windforce OC 3X model can be bought for $479.99 at Newegg right now.
It's priced at $499.99, but plugging in coupon code EMCDEGR43 at checkout knocks $20 off the price. The only way you'll find one selling for less is by trying your luck with an open box model, or hitting up places like eBay and Craigslist for a used model. This one is brand new.
Gigabyte GeForce RTX 2070 Super Windforce OC 3X | $479.99 (save $20)
This is the least expensive GeForce RTX 2070 Super available, and despite that, it's rocking a custom three-fan cooler and is slightly overclocked out of the box. Use coupon code EMCDEGR43 for the full discount.
Bear in mind that more demanding games need more oomph than the 2070 Super provides in order to maintain 60fps or higher at 4K ultra settings. But when Jarred reviewed the 2070 Super, he saw a playable average of 50fps across 11 different games. That is certainly respectable.
Reference setting for a 2070 Super call for a 1,605MHz base clock and 1,770MHz boost clock. Aided by a three-fan cooling solution, Gigabyte gooses the boost clock on this model to 1,785MHz. It's a rather conservative bump, but you could probably squeeze out a bit more overclocking performance if you're comfortable taking matters into your own hands (your mileage will vary, of course).
I haven't tested this card specifically, but have generally found Gigabyte's Windforce coolers to offer a great balance of temp control and noise.