The basic rare blind bag category is Wave 2, which saw a very limited release:
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loginOf those, the main character rereleases are of course the least valuable, since they differ from other waves' only in the accompanying character cards, which not everyone cares about to begin with. The glittery AJ/FS/Ry are (to varying degrees) similar enough to Wave 4 and the Target rainbow pack that interest in them isn't guaranteed. Blossomforth, Rainbow Flash, Lulu Luck, and Tealove have all been rereleased, though for all of them it's possible to tell from the hooves whether you're looking at a rerelease or not.
There were also a couple of variations within Wave 1: the glittery Twilight used to be pink, not purple, and she's much rarer that way, and there's some difference in Lily Blossom's shade of purple. From the character packs, Shining Armor has become quite sought after due to limited release and time passed since then. The Royal Surprise set has likewise been pretty limited, which mainly leads to interest in its Chrysalis figure; its Celestia differs from the Wave 5 one only in the hoof colors, and she's going to be rereleased in Wave 11 anyway, and its Twilight has some glitter on her horn or something unexciting like that.
Beyond that and various prototypes, everyone got more or less equal releases, so HTFness is going to be more a function of age than anything else.