Also, as far as the eye shadows go, Rich Core and Rare Earth MES are pretty much the same color, except the finish on the EDS is so radiant and shimmering, compared to the MES. If you love that color, get Rich Core and use it on the lid with Rare Earth in the crease - you won't be sorry.
Dark Dare - heavens to betsey, THAT is a black shadow. It's got a finish like wet asphalt and is so incredibly buildable. Or you can just wet your brush before picking it up for the thickest, blackest application in one pass. Puts other black shadows to shame.
Blue Orbit is just gorgeous. So is Young Venus, which is like Seedy Pearl entered the 21st Century. You really won't need Sweet Heat if you're getting Superb. Havana is very cool toned - didn't look that great on me, compared to Twilight Falls MES or Center Stage MegaMetal. Warm Thunder is the nicest grey/silver in a long time and is cool-ish but not so cool toned that it will look weird on warm skin tones. Modern Pewter is a lovely color, but it's like Dalliance (just a bit darker) - if Dalliance doesn't look good on you (it looks pretty bleh on me), Modern Pewter won't be much better. On the other hand, if Dalliance works, don't miss Modern Pewter. Grand Galaxy is another gorgeous purple to own. Lunar will make you drool if deep, jewel-toned blues are your thing - the texture is beautiful, and it's so buildable.
Personally, I'm getting Young Venus, Blue Orbit, Dark Dare, Rich Core and Grand Galaxy. I might also eventually get Warm Thunder, but I do have plenty of silver Crushed Metal pigment, from Surf the Ocean and also from the holiday stack with the white/silver/blue/black.
If you only could get one, I'd say get Dark Dare - you can apply it so that it looks more matte or more sheen-y or even sparkly, and you can apply it sheerly or build it up or just get a thick dense layer applied wet. It's the darkest and most versatile black eye shadow I've ever seen. If you never use black shadow, Rich Core, Grand Galaxy or Blue Orbit would be the way to go for a colorful one, or try Young Venus if you love Seedy Pearl. With the right skin tone, Modern Pewter will be the most interesting one, if you don't want DD.