So I listened to snippets of each song off ARTPOP on my alarm radio last night (I didn't want to listen to the whole thing). I noticed that even though I like every song except Dope, some songs sounded like smashes while others sounded like complete flops. I know that this isn't a good way of telling what will smash, but it was a little fun thing to do.
Here's what I thought sounded "right" or "wrong":
Aura: too EDM for the GP
Venus: This actually sounded like a smash on my radio. Maybe it should have been the lead or the second single.
G.U.Y. This sounded like a hit, but not really a smash. Might be easier to tell with the the radio edit I made, since the instructional voice makes it too weird for radio.
Sexxx Dreams: OMG SMASH!!!

Censored version is a mess though.
Jewels n Drugs: Urban smash maybe.

MANiCURE: Also sounds like a smash. There's nothing like it on radio right now.
Swine: Surprisingly, it sounded like it could smash. Probably shouldn't be released as a single though, since it will give certain people the attention they want...

Donatella: Hit, but IDK. Maybe it could smash.
Fashion: Maybe? I don't really know here...
Mary Jane Holland: Hmm... maybe. In Colorado it will smash.

Dope: Yeah, no. The GP won't be here for it.
Gypsy: SMASH!

"TONIIIIIIIIIIIIIIIIIIIIIIIIIGHT" sounds so good
So I guess Dope is the next single.
Edit: oh this drama. Maybe nothing will be the next single then. :\