Tomboyish Girl in Love, Apparitions Stalk the Night, and Extend Ash ~ Person of Hourai are rather nostalgic to me, since I first heard them in a bunch of Super Mario World hacks (which are also how I got to know Touhou in the first place).
Since Double Spoiler was the first official Touhou game I've seen gameplay of, it also feels rather nostalgic for me (particularly its music).