I think my favorite thing about crossdressing is the clothes -- getting to wear something pretty, like a dress or a skirt suit, with all the accessories, lingerie and heels... but not only the clothes, but looking like I belong in the clothes. I have often been complimented not only on my taste in women's clothes, but also because the clothes I wear fit my body -- like they were meant for me. And actually, that was the idea when I bought them!
For me, nothing tops the feeling of walking around in a skirt and feeling it against my nylon-covered legs... or the sensation of walking in heels, or feeling lingerie against my body and long hair on my shoulders... and knowing I put in an effort to look as naturally female as possible... that all contributes to a great feeling of satisfaction and happiness in me...