Our LFS has had some really nice bettas lately, and I'd always rather buy from a LFS rather than a chain store. It might be worth checking around to see who has one you really like. I know I've been to some stores that have "show quality" bettas (more expensive, of course). You may need to shop around for a few weeks to find the ideal one.
Always go for the healthiest betta you can find, even if it's not the prettiest.