On different occasions with different women I have been greeted by fully nude beauties, vixens in sexy lingerie, darlings in sexy business attire, girls next door in casual clothing (whereupon a joint shower was enjoyed), and one memorable time by a lovely dark-skinned honey sporting only a bright red g-string (the color contrast was mesmerizing.) And also, by pre-arrangement, entering a room to feast my eyes upon a delicious she-devil  enjoying herself (priming the pump, as it were) in anticipation of my arrival.  I prefer any and all of the above.  My only request is that she open the door.

I think it would depend on the woman. Something that accentuates her best features. Ex. Long legs=a short dress or skirt or maybe shorts with heels. But also something that maybe I don't get to see on a regular basis. Lingerie, stockings, a form fitting dress, great heels, short shorts, interesting panties. Something that would make my imagination race and something that I would feel is special for both of us.

You have a great one ...

LBD (little black dress)
LRedD
blue jeans and sexy top with little heels
blue jeans and t-shirt and barefooted
Sweat pants and work out top
sexy summer sun dress
Man's large long sleeve white dress shirt and nothing else
Yoga pants
Short shorts and sexy top or t-shirt
jeans, thigh high boots with heels and a sexy slinky top.
sexy, long flowing night gown with no undergarments
favorite colors - red, black, blue, purple

For me attitude is more important than what you wear. I will add that a skimpy low cut dress getting things going quickly

That's the first and foremost thing I'll see. I can tell most insincere smiles - turn-offs. If sight of me displeases you, say so and we can depart amicably with a broken appt fee/tip for your time. Fake smiles bother me.  
Otherwise with smiles, I dislike when providers have just scarfed lunch and have food bits stuck in her teeth. As you can imagine, those smiles are either grotesque or hilarious depending on her choice of meal. I have to admit a fave memory was one where the lady (whom I saw regularly) blackened a couple of her teeth - after dolling herself to the nines - just to see my WTF look.

Other preferences about what a lady wears (other opinions may vary)
Clothing - what we discussed via email/phone (my fantasy) or something close to your ad/website pics (because your marketing photos work).
Perfume - light smell, if any. Bath & Body Works scents are fine too.
Make-up - light.
Jewelry - none.
Shoes - I'm not into shoes, but I dislike thick soled/hi-heel shoes. Flats work just fine. Height or lack thereof isn't a concern of mine.
Mani/Pedi - clean, groomed nails. I'm not into artwork on nails.

I can't think of what else a lady might wear when she opens the door. Hope this helps.

Kosh

Heels, Thigh Highs, Lace bra and panty set....

I would prefer for them to be totally nude when they come to the door. However, since I prefer outcalls I'm guessing that my preference will never actually happen.

I would say a teddy, black thigh highs and high heels. There are also times I had models open the door with nothing on, especially when they knew it was me again. Then some models wear a sexy dress, high heels. The first thing though is a smile.That sets the mood all the way