I think the brown or the bright blue just under it. May creating the "big boy" quilt ease your heart and mind. Be gentle with yourself and after a time you may be blessed again.

I love the vertical colors you have chosen and I agree with you. The bottom horizontal one goes extremely well.

I like the bottom fabric best. Hope your busy hands help in this painful time.

Are you doing this as a quilt as you go? Quick and easy.
1. Cut out batting and a backing colour same size as front
2. Start at the step side left at the top.
3. Place first piece bottom batting top as if a sandwich . Place top of next piece right sides together .
4. Place batting on top of the second top.
5. Place back piece right side to right side of first piec.
6' machine all together I would use 1/2incg seam .
7. Press well.

I am sure you get the idea it does grow vey quickly and you can trim seam if you wish.
You can also quilt a design on each section when sewn

I like high contrast. I think the bottom blue may be the same value as the verticle brown. I think the top two/left have the most value contrast to the two verticle. I don't know the pattern you mentioned, so I'm going at this like a mystery quilt. It's have do make decisions without the pattern. I think high contrast is more masculine for your boy.

A gentle and soothing combination might be the ferns and bottom blue.

I also had a SAB and it took a long time to recover.

I originally liked the ferns until I did what lakekids said and she is right, so I vote with the bottom blue and top brown. Sorry for your loss.

Be sure and give your mind and body time to heal. Your little guy will keep you occupied as well. The fabrics are beautiful. I am truly sorry for your loss.