There are a lot of different types of batting, and usually your choice for a quilt is just based on preference. There's really no best batting to use as determined by a particular size quilt. Other projects, like home dec or quilted garments, do have batts that are preferred one over the other.
Some of the things to consider are:
-batting content: do you want a breathable natural fiber or poly? Cotton or cotton blends are the most popular and reasonably priced. Wool, silk and bamboo are all wonderful batting but pricey.
-loft: do you want a puffier quilt or something a bit flatter and antique looking. Cotton is a flatter batt, but it does come in different lofts, Warm and Natural vs. Warm and Plush. Wool is fluffier. Poly is probably the puffiest.
-Quilting distance. It is very important that you understand this term and the requirements of any batting that you finally choose. The packing will tell you the farthest distance apart your quilting lines can be. There are some batts that need to be quilted as close as 3 inches apart, some that can be left unquilted for up to 10". Make sure you measure in all directions.
WM & JoAnn's both carry several brands. See what brands are available at your store, then do a bit of research on the company's web site for more specifics. Here's a link to the Warm Company. Lots of info:
https://warmcompany.com/