I had both an Eon Core and an i770r. I did probably a few dozen dives with both, happy to try and answer any questions you might have on either. Also, I used to have a D6i, and while the watch-like design is convenient, in the end I preferred a bigger, color screen.
Air integration was a must-have for me-- once I started diving with AI units it was hard to imagine going back (though completely understand those who prefer an analogue gauge).
Size and weight-wise, there wasn't much daylight between the two, same with battery charging, etc (though I will say that after a while without being used, the i770r did have much more battery reserve left than the Eon...but I'd charge them fully before using anyway, so that's not much of a factor).
A couple minor plusses for the Suunto: I found the buttons *much* easier to use and the menus were, to me, more intuitive than on the i770r. That said, I think after enough dives using the i770r exclusively, you'd get used to it and it'd become second nature. Also, I strongly preferred the compass on the Eon to the i770r.
A couple plusses for the i770r: the NATO strap is a lot easier to use and manage than Suunto's rubber strap, which always seemed difficult to wrangle. It comes with a nice case, which the Eon does not. I also liked the font a little better.
As you can see, once you start listing font preference, you're really scraping the bottom of the barrel- at the end of the day, I would have been really happy with either.
I will say that the Suunto's algorithm was more conservative, but I'm never really pushing any no-deco limits, so that's largely irrelevant to me.
Sadly both were stolen about a month ago, along with most of my other gear-- I ended up getting the Eon Core as a replacement, and that was just because of cost: my LDS here in Tel Aviv had it for a few hundred dollars less than it would have cost me to replace the i770r.
Again, hit me up with any specific questions, I'll be happy to try and answer.