I would clean and paint the one you have. It will be gorgeous, once its cleaned. The other one is very modern, and appears to be an electric type fireplace, or possibly gas. Yours looks to be wood burning, and it also fits your house (what I can see of it), more than your inspriration pictures.

Very cool mock up and walk through! It looks like it’ll be a space you will enjoy. If I were to be rather picky, I’d say the bar stools by the back tv area seems a bit crowded… but it could just be the picture/ software. In the mock up it shows a back splash on the posts… I’d probably remove that. And if were my space, I’d move the stove top to the wall instead of in the Island and hang some nice lights there instead of a vent hanging down. What an exciting space!

We went with a large scale textured tile, It really all depends on what interior decorating style you like. Theres huge differences in what you would use. You have a pretty blank slate, what materials or styles do you guys like? We have a more coastal look that has lighter woods, whites whites, creams and some gray. If you figure out what you love, you can go from there. You might find that the stone will work but id look at different materials

A mantle that is only 72" long and 8x8 seems like a terrible proportion. That's like a railroad tie. Have you actually drawn this wall elevation on paper so you know where the tile begins and ends in relationship to the firebox and all the other elements? No one likes surprises. Good design doesn't typically happen because you think it up. It gets drawn up & the details get worked out on paper before you swing a hammer. Also, the Schluter edge required comes in scores of colors, but some of them have to be specially ordered. If your tile is charcoal gray, you might want the matching charcoal gray Schluter edge. Think ahead! You can purchase ready-made mantles like you see above off Amazon