This is just my opinion, so use it if you want...etc...
Your block is busy enough that something complicated would only make the quilt busier. I'd take what you have from any of the more neutral fabrics in the quilt and go around the whole quilt with 1 1/2 to 2 inches. This is done to distance the blocks from the edge.
2nd border is a framing border. Take one color....doesn't even have to be the same fabrics, maybe a darker green and make a "framing border of 1 inch to 1 1/2 inches. Your eye will go to this border first. It will be right on the edge of the bed if you can know what bed it will be on ahead of time.
3rd and outside border is the largest. Depends on how big you want the quilt. This would hang over the edge of the bed. Depends on what you have left. It could even be a print.
Please let us see what you come up with.
I agree with pewa88. Put it all on the design wall and pin things and audition them.
Above all .....have plenty of fun.
Marcia