I thought I liked the silver star wand best (and I'd still take it in a heartbeat), but the purple flower wand just looks so GOOD. I'm actually surprised it's the least favorite of the imposter wands, wondering if the OG flower wand has any influence on that. It's very Aerith-core so I hope to obtain it one day (unless they release a red glow wand... neeeeed)
I'm not going for any of these Impostor Collectibles since I'm focusing on the Black Feather and the White Feather, if I can even manage to afford both.
But, for the sake of answering the question, my favorites of these collectibles listed are the Cyan Heart Wand and Inky. The Cyan Heart Wand would be nice for one of my lineups, while Inky is a ghost, which obviously appeals to me, and I think I could work him into a different lineup as well. If I'm just choosing one...probably Inky.