T-shirts since it gives the "I'm casual but I can still be sexy" type of feeling - it can be one of those shirts that are too big for her that she wears almost as a dress so it just drapes over her curves but you can see, or just a casual tee that kind fits snug. Tank tops are nice too.
But also form fitting dresses, tight ones that are almost tight like spandex can be sexy, but I like the semi formal dress that isnt too cleavage revealing but leaves a little to the imagination...but then again that's a whole other debate for me because I like seeing ladies in backless dresses.......
anyway I digress
The button down shirt is nice too - in hentai/anime - its nice to see the impossible clothing type with the 3 top buttons undone so you can clearly see the cleavage, but IRL - I like the drape like a dress type again
EDIT:
Button downs:
Shirts:
couldnt find dresses