That one pony you always keep, even though you already have several?

[TinyShinyUnique]

G3 Starsong and Rainbow Dash. I haven't been planning on having an army of them but each time one of them lands in my hands, i can't get myself to sell them or to pass them

[Skeen]

Milky Way and Nightglider.  They just look so nice together I feel bad splitting up any of my "sets."