As Suern3 posted, Quilters Dream Poly is very nice. It feels very much like Hobbs 80/20 in density and drape. I also use Hobbs Poly down quite a bit. It is more lofty than the Quilters Dream. Hobbs takes use and several washings to soften up to a nice drape and quilts very flat when densely quilted. I like both equally but tend to use more Hobbs polydown than Quilters Dream.
Edited to add, here are links to several quilts I have done using Hobbs Polydown, although none of these are T-shirt quilts it should give you an idea of how they look quilted up.
"East Meets Midwest" an Asian scrappy quilt
Retirement quilt for a coworker
4 Patch Posy quilting
"Bali Cats" pieced and quilted by feline fanatic