Generak HNNNNNNNGGG aside, I think Chihiro has more possibility of becoming Goddess. The reason for it is actually.... due to the fact that Ayumi has more chance of becoming actual heroine of all conquered ones this series.
Well, let's revise what Wakaki said about the theme of this series;
"Dying as Capturing God, or Living as a Human"
This is supposed to be summarising plot of this series. Just think about it. What is happening to characters who ended up becoming goddess? What happen to Tsukiyo after being revealed to be goddess? What about Goido Yui or even Shiori and Kanon? Yep, they haven't been appearing to the scene for a long time.How about ohter heroine who is revealed to be not a goddess?They got very, very small amount of scene and just forgotten. Like teacher and swimming girl.
It is very clear that the one heroine who will be critical to the storyline will be someone who isn't goddess, but getting spot light at the SAME TIME. That means, it is either Chihiro or Ayumi.
The thing is, Ayumi is officially Wakaki's (Author's) FAVOURITE CHARACTER. Every single of his fetish and personal preference of female basically condensed in the character of 'AYUMI'. We all know that Genius Wakaki was thinking about this goddess plot since the start of this manga's serialisation (Wakaki said it himself. He said he already had idea of goddess, he was just calculating the right timing to introduce them.).If you see the first chapter clearly, you will find her response to Katsuragi was actually not that negative. Even though she called him otamega or other things, she seems to be very friendly to him and talking to him very nicely. Even drawing heart when giving her brooms to Keima.
Now, the theme I mentioned above. Katsuragi will ultimately get a decision to take (like Wakaki himself had to do in his life. We all know Keima = The author himself. u.u~~~) - his fantasy or reality. At the end, the girl who is really important will not be goddess, but someone who is in 'reality'.
Lastly, look at the picture I posted. I think in situation like 'that', is almost at the same level as kissing. Goddess is supposed to appear already, imo. It didn't. Thus, Chihiro is more likely to have one.
(of course, my prediction can be horribly wrong.)