Ok I love my FO sights. For tan targets green seems to be the favourite colour I see at matches.
There is an alternative that I fell into though. If you do settle on a model of the S&W M&P (CORE if you really want an Optic) here is something to consider before you make up your mind on where to spend your dollars. Go to a hobby shop and pick up a small bottle of red fluorescent model paint. Take a toothpick and dab the end in the paint and then tap the toothpick on the white dot on the front sight your gun came with. You will find the paint on the toothpick will drop nicely into the concave of the front sight. Make sure the face of the front sight is clean and free of oil.
With a bottle of Black model paint, paint out the two white dots on your front sight.
Go to the range and see how you like the sight picture. Frankly, I could have saved myself a bunch of money by doing this before I chased down FO sights. I am no saying FO isn't worth while but I am saying the drop of red paint on the front sight is quite a nice sight. The dot really does jump out at you. Try it you may like it and if you don't nothing ventured but a few dollars in paint. If you go optic you will be chasing the dot and won't use the notch and post sights anyway. If you don't go Optic and I would recommend you don't initially, then give the red paint a try. You might be surprised. I was.
Take Care
Bob