A few months ago, I would've said save up a bit more and grab a used 3090 as it'd blow the doors off either of the aforementioned all with more VRAM (though heat on 3090s tends to be an issue, but not enough to not buy one at a good price.). But obviously the whole AI push has driven up the prices of top-end cards again, probably even worse than mining did. Both of my GPU's have gone up about a $1,000 or so dollars since I bought them a four-ish months ago.
That being said, with Daz, VRAM is king. Cuda cores do matter, and the 4070 would be slightly faster as a result (if I recall, don't remember the exact cuda core amount for either), but Cuda cores only matter if you're actually able to render what's on the screen. When you're saying 8 characters, are we talking Genesis 8, 8.1, or 9? 9 is going to be largely off the table for either of those GPUs, you might be able to pull 4 8.1s with the 16GB of VRAM + a solid environment. Working with Genesis 8 is probably going be the safest, especially if you go for the 12GB card.
