It is a personal preference. Some are cotton purists when it comes to thread and material. Some mix it all up. So far my quilts are made to be used, abused and loved... so I choose to use cottons and cotton threads and hope they will hold up to all of that loving :D :D :D
Polyester and poly blends tend to fray more, and a 1/4" seam may not be enough...typically you are using a 5/8" seam allowance with these.