Low light SLR
In addition to what the guys said, you need a "good" low light sensor to produce quality images with the least possible noise and much details and among your chosen bodies the D7100 is a good compromise unless you wanna spend a fortune on a top end FF body and a lens.
|_F0A5334-Edit_small by Dester Wallaboo|
from Open Air Fashion Photography
|Feed me, me, me, me, me by Denjw|
from Attention-Seekers in Nature