While the specs are basically the same, I think the faceting pattern on #3 is cleaner and prettier. I'm always a tad suspicious of diamonds when you can't see all the arrow heads at the one time. Lacks balance. I could be wrong, of course, and it could be tilted slightly off center. But I like the nice, strong pattern of #3.
On the other hand, if your partner is choosing on the basis of specs, rather than visuals, she might prefer #2, given that it's larger and the only one on the list to break 1.4ct.
If your partner hasn't seen a lot of diamonds, she probably doesn't realize that a flawless diamond and a VS2 diamond at this size, all else being equal, will look identical to the eye. The difference she can achieve in size, on the other hand, would be remarkable. Also, a lot of people find an E color blindingly white (it is), but a D - cold and hard looking. Most people, on the other hand, can't tell the difference.
I'd advise you both to go look at some diamonds at a reputable store that specializes in diamonds. I mean, if you're all about the numbers, is there some reason you're not dealing with a company of diamond specialists, like WhiteFlash, Crafted By Infinity, Brian Gavin Diamonds, Good Old Gold, or Victor Canera? Until you break into the world of super ideals, you're not really getting the best out there. The stats on the diamonds you've shown us are definitely in that range, but there's still variance, and until you've seen a few super ideals next to diamonds that...aren't...you won't be aware of the difference. And it's a difference you'll actually *see*, as opposed to your D vs E or IF vs VS2 - which you won't.
