I have never gotten monofiliment to work well for me. And I am afraid of it breaking and pulling out in the future.
I have never had a problem with quilting with colored cotton or cotton/poly or poly thread, and I really like how it looks against a quilt top. I pick a coordinating color, or a somewhat neutral color (i.e. taupe or gray) depending on the effect I want. I have really enjoyed watching a somewhat neutral looking quilt come alive after being quilted with varigated thread, for example. It really makes a difference. Don't be afraid of your errors showing...that's all part of the process. No one but you is going to criticize it.