I'm still going to buy and play it either way, for sure - Larian already has my money. But I really just want actual D&D in a video game for the first time ever.
I think D&D done in RTwP with full D&D rounds happening in the background is actual D&D. In the same sense, having game AI isn't perfectly identical to having a human DM. The same is true for various other aspects of any D&D video game.
That said, TB-only D&D has been done in a video game before, and you can currently buy it on sale at GoG for 75% off:The Temple of Elemental Evil
If you get it, there's a community patch that people recommend. There's a link to it in the GoG forum.