That surround is totally wrong for that FP and surrounding book cases

staining it darker won't help.

The bookcases are too traditional for the shiplap fireplace surround.

Looks like you are trying for a classy look with the decor and piano, the fireplace is out of place.

You need to remove the shelving that's currently there and replace it with floating shelves. You also need to replace the existing doors on the cabinets next to the fireplace with something more updated.

The shelves and cabinets could be painted a matte black to coordinate with the black tile surround OR are you planning on replacing the black tile fire place surround?

Do you have another area in the house for the piano?

Your new wall is great and looks nicely done. It does clash stylistically with the side units and maybe with the shiny tile surround, but we don't know what your plan/budget is, if any, for those areas.

Your question was which stain to go with. While I get your instinct of going darker, a tall shot of wood-tone rising up from the differently-toned wood floor is probably not the way to go at this point. What looks kind-of-okay in a small sample could end up as a clashing tower. A lot depends on what else you have going on in the adjacent areas. Do you have any other natural white oak around? Other stained oak around? It needs to relate to something.

Are you starting to shift your whole house towards a more modern aesthetic? I see a little railing up to the left, so I'm assuming it"s a pretty open area. Walls look like a very tradional yellowish cream. A lot depends on the entire space.

If at all possible, I would at the very least do some tweaks on the side units. (if they're staying)....

I would replace the crown-type molding along the tops of the units with a similar profile to the top of the new fireplace wall, and also if possible the molding edge right above the old doors.

Flat panel doors on the units would be an improvement. New hardware?

I would even-up the shelves (eliminating the staggered effect) and really, really edit the stuff down. Consider eliminating the hanging plates, for example.

Right now there's just nothing uniting the new center with the old sides. Deal with the moldings/profiles/ etc., to get them at least in the same family, then think about color. Does the white match the trim you have going on elsewhere? The blue (very pretty) background with white cabinetry screams traditional. That needs to be looked at before you decide on finish for the center.

Maybe some views of the entire space as well as some idea of your general appetite & budget for more changes would help people provide more useful advice.

OP where are you we need feedback

I say the special walnut looks better than the clear. It would also look nice painted the same color as the inside of your shelves.