Assuming square footage, moisture protection, etc is the same, would there be a significant difference in overall price between installing:

3/4" medium grade, site finished Red Oak with honey stain over existing plywood

vs.

Medium quality red oak engineered over existing plywood

In N. Ca., site finished floors are often more money due to high labor costs. However, I see you are in Florida. You need to check with local contractors to determine cost differentials. Also, cost of prefinished engineered varies greatly as well. In some places where labor is cheap, finish in place is less; and visa versa. It used to be about a wash around here but not so anymore as prefinished cost have remained reasonable and site finishing costs have taken off.