Body. Pure sexual attraction for me requires a healthy body.
Face. That’s the part I’m going to look at 90% of the time.
And by amazing you mean what?
Tall, toned, athletic. Defined arms and legs, but not gymratesque. In fact, you get too Men’s Fitness looking, and it becomes a turn off. Ideally a guy’s body would be taller than mine when I’m wearing heels, with broad shoulders, medium-to-large build, and fit. One jillion bonus points for having hair on the arms and chest.
In my case, that would the the top of his head. 
In general I’d have to say body. I’ve been with guys who had ugly faces and hot bodies, and they’re always better in bed than guys with gorgeous faces and ugly bodies.
Now that I think of it, I’m more of a parts person. The face doesn’t have to be heavenly, but the eyes must. And I don’t really care too much about the body, but I like a nice ass on a man (nice tits on a woman). I guess if I had to pick one, I’d go with the face, but they’re, on the whole, pretty even.
Hetero male, 44
Body.
My reasoning is that there is a very wide range of face-types that I find attractive, but a fairly narrow range of body types that I like. Since the OP specified “would you rather be having sex with”, I’ve got to go with body. As an example, immense breasts are a complete turnoff for me (I know, I’m apparently weird), and so no matter how attractive a woman’s face is to me, I’m just going to be completely put off if she has huge breasts.
Face. Being attached to a beautiful face is part of what makes a beautiful body beautiful.
I’m not picky. Anything under 300 lbs is enough, I don’t care about the face, and exceptions to rule #1 can be made.
So the choices are:
a) beautiful face (where the body is also acceptable)
b) beautiful body (where the face is also acceptable)
My answer is yes.
Seriously though, where’s the downside to either option? The mitigating factors here are intelligence and personality. I’d probably have to go with a) the face.
Face. I love a good body, but an ugly mug is just too hard to ignore. I had a previous relationship with a less-than-average face, and it’s really hard to be intimate, good body or not.
34 year old male.
Face. You see it far more often.
For a purely casual sexual relationship–body.
For something more–face.
Though I will say that there are many cases where a face can be sort of homely in an attractive way. There was a guy I had a FWB relationship with for nearly a year all told who had one of those types of faces. If I had wanted a more serious relationship, his face would have been perfectly acceptable but not without that amazing body.
A personality container! I love it.