I would take the RTX 3090 over the RTX 4070 Ti any day of the week and twice on Sunday. The performance will be about the same but there's a BIG problem with the RTX 4070 Ti, the lack of VRAM.
The RTX 4070 Ti has only 12GB of VRAM and that's not nearly enough for a card with its level of performance. The RTX 3090 has 24GB of VRAM, which is probably more than it needs but it's the less expensive card so who cares? The fact that the RTX 4070 Ti only has 12GB of VRAM while the RTX 3090 has 24GB means that the RTX 3090 will live a lot
longer than the RTX 4070 Ti.
What good is 4K and RT performance if your card doesn't have enough VRAM for it? Just look at the joke that has been the GeForce lineup over the past two generations:
RTX 3050 - 8GB
RTX 3060 - 12GB <- I still don't understand why nVidia did this.
RTX 3060 Ti - 8GB
RTX 3070 - 8GB
RTX 3070 Ti - 8GB
RTX 3080 - 10GB
RTX 3080 Ti - 12GB
RTX 3090 - 24GB
RTX 3090 Ti - 24GB
RTX 4070 - 8GB <- Expected because of information leaks
RTX 4070 Ti - 12GB
RTX 4080 - 16GB
RTX 4090 - 24GB
Now look at the Radeon equivalents:
RX 6600 - 8GB
RX 6600 XT - 8GB
RX 6650 XT - 8GB
RX 6700 - 10GB
RX 6700 XT - 12GB
RX 6750 XT - 12GB
RX 6800 - 16GB
RX 6800 XT - 16GB
RX 6900 XT - 16GB
RX 6950 XT - 16GB
RX 7900 XT - 20GB
RX 7900 XTX - 24GB
The RTX 4070 Ti has 12GB and costs $800+
The RTX 3060 has 12GB and costs $343
The RX 6700 XT has 12GB and costs $345
Do you see a problem here? I sure do!
screwed when it comes to VRAM if you have an RTX 3060 Ti, 3070, 3070 Ti, 3080, 3080 Ti, 4070, 4070 Ti or 4080. The only cards that guarantee that you'll always have enough VRAM are the RTX 3060, RTX 3090, RTX 3090 Ti and RTX 4090.
I would take double the VRAM over better RT performance and DLSS3 without hesitation. The lack of VRAM on the GeForce models I listed is guaranteed to cause problems long before the GPU is no longer potent enough for 4K gaming. The RTX 3090 will be a good 4K gaming card long after the RTX 4070 Ti is relegated to 1440p. The difference in VRAM is so big that the RTX 3090 might be able to still game at 4K when the RTX 4070 Ti is no longer able to handle 1440p.
When choosing a card, ALWAYS take the amount of VRAM into account because the amount that a card is born with is also the amount it dies with. Software frills like DLSS and RT can always be improved but the amount of VRAM a card has can't be.
Hope this helps you!