seems like there are people who will say..."cotton is best" and there are those who will tell you "poly is best"...then there are those of us who LOVE the wool batts and the bamboo's...it depends on your personal choices and what you are using them for. I do not believe one is necessarily better than the other; just different. I use them all. I love wool batts and use them for really special quilts (because they are expensive) I ABSOLUTELY LOVE DREAM POLY!!! oh my it is a dream to work with! i use WARM AND NATURAL cotton batting most often...the dream poly is as thick and wonderful as the best warm and natural, biggest difference (2 of them) 1) warm and natural is cream colored; dream poly is white...2) warm and natural shrinks just like all cotton battings; polyester battings do not shrink.
poly's are great to use in kids quilts or any quilt that will be laundered alot; it holds up very well and washes thousands of times without issue.
not all cotton (or any other batting) battings are created equal, some are better for hand quilting than others, some are better for machine quilting; some are ok for machine quilting with a small machine but not so great with a long arm...
i have put together a little (scrap/swatch book) journal if you will...each time i try a new batt on the market i cut a 6" square of it to add to my book, noting the recommended quilting distance, laundering instructions, material content, cost, and then after i've used it i add my critique and general feelings about it. some times it lets me know i never want to use that again,or perhaps i oh so love it and will look all over to find it again.
i do not think anyone should limit themselves just because someone said ... this is the only batting i would ever use in one of my quilts...how sad :(
there is a wide world of quilting out there and you should try as much as you can and make your own decisions what to use and what you don't like.
there is one cotton batting out there i ABSOLUTELY HATE!!! but i have a friend who loves it and would bring it to me with her quilts to be quilted...i kept replacing it (at my own cost) finally when she was over bringing me another quilt we talked about it and i had just finished a quilt for her mother that i did use the hated batting, so i could show her exactly what my issues with it is and why i shudder when she brings in a new quilt to be quilted. she understands my side now and has assured me that neither of them will buy that anymore. (they would bring me a quilt and tell me don't quilt it much, it doesnt' need much...but the batting said quilt every 2"...so i had no choice but to do some heavy quilting...finally she understands; and we had talked about it a number of times but until i could show her...)
anyway. try every batting you can get your hands on and make your own decisions based on what YOU like. (the dream green batting which is green and made from plastic bottles is just like using artic fleece for a batting)