That being said, I like using Gandi knowing they support (financially or otherwise) many amazing open source projects and organizations. Those that stand out to me include Debian, EFF, and CC, but I recommend you take a look at the full list[0] on their website. They also take a strong stance against SOPA[1] (and clones) and prominently display their no bullshit stance[2] on their website and merchandise.
There's also a bit of a bonus if you're slightly tech savvy because you can often find their devs on Freenode at #gandi-mail or #gandi-hosting, though it's not advertised and there's no guarantee.
[0] https://www.gandi.net/supports/
[1] http://www.gandibar.net/post/2011/12/23/Gandi-s-Opposition-t...
If you want to use my referral link [2] you can register or transfer a domain for $5.
I'm also a big fan of Hover [3] and Namecheap [4] too. I generally want a no nonsense, no annoying upsells, simple domain registrar. You also should think about what TLD you want as different registrars will have different TLDs especially now that the new GTLDs have arrived.
[1]: http://badger.com [2]: http://badger.com/derek [3]: http://hover.com [4]: http://namecheap.com
(As a meta-comment, whenever VPS comparisons are brought up on HN, it's always Linode vs Digital Ocean. Gut feeling to compare apples to oranges for domains providers, Gandi is Linode while iwantmyname is the Digital Ocean)
They'd be fine, except that if you use their DNS servers, they by default add a wildcard record pointing to spammy domain parking pages, breaking NXDOMAIN. And don't expose it in the UI, so that it's very easy to miss that they're doing it and not easy to figure out how to disable it. (Answer: by adding a wildcard TXT record).
Referral link: https://www.gossimer.com/aff.php?aff=253
I only do 10 year registrations (SEO) and NameCheap has a big discount for those.