Raina!Less common, *and* she'll probably have her name spelled right more often! (Whereas with Allison you also have Alison, Alisyn, Allisyn, Alyson, etc.) Not to mention Madison, Addison, and a lot of the other -son names that are so common for girls today.
Raina, hands down.It's simple and attractive without being too popular, it isn't trendy or at all modern, it couldn't porribly be called dated, and it has a nature connection with 'Rain'. I'd love to meet a Raina (I might even use it myself) but I'd just groan if I met another Allison.
Raina or better: RaynaI'd vote for Raina.I like Allison, too but it's pretty common. Raina definitely isn't! I like Rayna spelled that way more though. Raina reminds me of rain which is a kind of depressing connotation.