My thoughts would be to use the same colour for bobbin and top thread ... shows less if there's any mis-fires on the tension!
Your backing is a pretty strong colour (I really like it!). You may want to choose a heavier thread for the quilting to help it show above the pink; and then use a regular thread on the bobbin.
How about a dark green or dark purple?
Or perhaps you might use both selectively for different parts of your design?