As you see, you will get lots of different suggestions. Here I go with mine. I would first consider what you re going to use for your back. I like to use that color either in my border or as my binding. I like the what border even though there is a lot of white in the top already. It keeps the "theme" or the look of the quilt and border looking consistent. But, I would suggest a narrow color border first, then the white.When I first looked at your quilt I saw green but that could just be because of the photo. So if it was my quilt, a narrow green border then a white wider border but not too wide. If you wish the borders to actually make the quilt larger expand both the inner border with just a little and the same with the outer border.
There you go my opinion. Put it in the bag, mix it up with the other ideas and do what feels good to you. You have a lovely quilt started and oh, so many more quilts in your future to play with.