maybe rare is the word i'm looking for. i'm pretty sure a large majority of people here own the champions that were brand new when they started.
Ziggs and Nautilus were new when I joined; I tried both of them when they were free but the whole champion release thing was new to me. I didn't actually get Ziggs until a couple weeks before Pool Party; I still don't have Naut.
Fiora was the first champ that I noticed the release of; just got her recently but she's still awful and I couldn't really care to learn her. Lulu was the first champ I had to get upon release; ended up getting with IP a couple days late but she was a lot of fun. Lulu is actually my most played ranked champ by a good margin. Zyra was the first champ I got the bundle for and my most played in Season 2.
LoL Board: Zyra, Ahri, Syndra, Diana, Elise, Sejuani, Shyvana Pokemon X Board: Candice is mine.