The brown/cream/tan brick is so much easier to live with that my first thought is to paint the red brick to match a light color in the brown/cream/tan brick.

I'd paint all the brick white. A nice bright clean look especially in a basement.

I live in a neighborhood where that original red brick is something people buy homes for. Now what?

You could just paint the fireplace brick and not the red brick. That could look interesting and make both elements, the fireplace and the wall stand out.

any suggestion on what color to paint the fireplace? A thought was german smear

I'd be tempted to whitewash or German smear all the brick, you could add a bit of shiplap on fireplace to break it up. Be bright and airy

Depending on how much you want to spend ... you could encase the brick fireplace in wood. There are so many ways to do it. Classic look wood & molding painted white , ship lap painted white or rustic wood design. I would leave the brick wall unpainted & seriously invest in boxing in the brick fireplace with a different material rather than paint. I think it would take away to paint it all or even paint the fireplace leaving the wall untouched. Keep up updated on what you end up doing.

Keep the red brick since it is a regional thing. You don't want to possibly hurt the future resale. I would not paint the brick fireplace. Brick is not meant or made to be painted. I know that many will disagree with me, but painted brick looks cheap and boring and once you paint it there is no turning back. I wonder how many people in 5- 10 years will wish they would of never of fallen into the latest fad and painted their fireplace. I would stain the brick, not the mortar though.

If the red brick is a desired feature in your area, I would clad the FP in a totally different material. Mismatched brick no matter, will look "wrong". How about covering the FP in copper?

I love all your ideas but I am on a tight budget

The fact that they are two different scale bricks is the issue. One has to go. Up to you/budget what makes sense but trying to keep both as is and just painting one isn’t going to cut it design wise.

I love my painted brick fireplaces... but they're not next to a different kind of brick. In your case I would clad the fireplace in wood.