S.E.
Oh, I feel your pain! We went through your exact same situation a couple of years ago. I too grew up in MO and thought the school system was absolutely fantastic. With my oldest, now entering 2nd grade, we really struggled whether to send him to private or to public. We too live in Plano ISD. We actually didn't make our final decision until a week before school started because we were so on the fence. We decided to go the public school route and put all of the money that we would have spent on private school tuition into a fund for his college so that he wouldn't have to worry about any student debt.
I agree with the other response that the individual teacher makes a huge difference. Our first year, the kindergarten teacher was less than stellar. We thought we had made a huge mistake and started researching private schools again. However, our son expressed how much he loved his school and all of his friends there, so we decided to give it one more try. The teacher he got for first grade was absolutely outstanding. Not only did the parents all love her, but all of the kids and other staff members did as well. In addition, we hired a private tutor over the summer to help keep his reading skills up and we will continue with her throughout the school year, just to give him the extra individual help he may need.
Our youngest son is starting kindergarten this year with his older 2nd grade brother at a Plano ISD elementary school. Looking back, I am really glad we made the decision to stick it out in public school. I feel like not only are they getting a great education, but socially they are growing at a rate I don't think they would at a private school. They are exposed to a much broader range of different religions, races and socio-economic classes. I don't want my children growing up in a bubble, not exposed to all of the great differences our country offers.
When it comes down to it, do what feels right for you and follow your gut. In our case, we decided to go the public school route after much debate and it worked out well for us. Good luck in your decision making! It's a big deal sending your baby into kindergarten! :o)