Rarity/Applejack: They are, technically, the Elite City Dweller and the Country Bumpkin. Rarity has grown up with a value on aesthetics, probably enjoying accessorizing and man-made beauty, while Applejack probably enjoys watching sunsets and the river flow. They'd have their differences, definitely, but i think someone working in Rarity's field (fashion) would appreciate Applejack's honesty. Applejack would probably find some of Rarity's quirks and interests a bit odd, but cute. I don't know if they'd be able to overcome how different their approaches are to things, but I could see that glimmer of attraction there. This wouldn't be a passionate pairing in the smoldering way, but it would be one of intrigue and lots and lots of learning on both sides. ♥♥♥/5 pony hearts.
Rarity/Rainbow Dash - Rainbow Dash is, without a doubt, lacking in the etiquette and tact that Rarity cherishes so much in her generous approach. Heck, even after the dragon incident, Dash thought what Rarity did, while nice, was a bit of a waste of time. Rarity has patience and looks at the intricate details in things, while Dash likes to get dirty, is boisterous, and kind of belligerent. They both have a bit of an ego issue, and I think they would get into very small competitions. I think Dash might be one of the only ponies that could tick Rarity off a bit, make her lose her composure. Strong "Lady and the Tramp" feel, which makes for good stories, but does it make for good ponily-ever-afters? ♥♥♥.2/5 stars.
Rarity/Pinkie Pie: They both are engaged socialites, but Pinky is wild while Rarity is cultured and more astute. They'd click well, I think, as friends, on numerous things, but in the end Rarity might not enjoy being with someone who takes so much of the spotlight off of her, even if she did admire PP. Score: ♥♥/5 pony hearts.