For me it's my waist, arms, and thighs.
I lost most of my poundage on my waist, then thighs, then arms. And I got extremely 'firmer' and stronger around my waist, upper arms, and thighs also.
I can almost not believe how much more I can carry, or how much my thighs can squeeze, or how hard my side core muscles are now! Before it all used to be like poking jelly.
I haven't lost enough yet to know how I am going to look at my goal weight. I am hoping (extremely) that I don't have any loose skin or pooch (mostly because I am only in my 20's). I want to be able to wear a bikini with pride before I turn 30! I just need to melt the fat around those newly hard muscles!!