hehe bro I have the opposite problem: my delts grow like fucking weeds (see avatar with only indirect delt training) but I can get my damn abs or chest to look right.
edit: my three are abs, chest, bi peaks. Oddly my calves have always been pretty big and symmetrical
I never really train abs directly, they are ok, i just need to get really low bf for them to look sick but im too lazy right now and wanna add more mass. Might cut up this summer tho...
quads and hamstrings, I have started to work them fuckers a little more intence and I am seeing improvement, but my genetics are just not there. My grandpaw had small legs. Next I would have to say abs and then shoulders.