All good quality flannel is about the same. They are great for backing baby quilts, and now come in so many patterns and colors the choices can be daunting!
Just make sure that the flannel is thick and soft before you wash it! It will shrink quite a bit, so be sure to buy plenty if you wash all your material before making the quilt.
I am finding that the cheap flannel just does not last and will fall apart after a few washings, so spending a little extra on good quality flannel (may not be the most expensive either!) is well worth it.
Happy quilting!