godaddy sucks
Google and you will see Godaddy reviews
But yes, they have acquired a good market I know that

I think popular and biggest have a bit of difference. By being popular, you are probably referring to being well-liked by people, which GoDaddy doesn't seem to be in such a position.

I'd say GoDaddy is the most popular, while Enom seems to have the most distributed 'popularity' (i.e. resellers using their API).

Its Godaddy But personally I do not have any domain with them and do not trust them much

Personally, I prefer Name.com....

Godaddy is the largest but I go with namecheap.

I would say that Godaddy would be the most popular.

We personally use Namecheap.com for all of our domains. As tempting as GoDaddy is on some of their pricing, I have personally always believed something was fishy with them. With their support of SOPA, my hunch was right.

Currently, no one is able to match the pricing we get from Namecheap so we wont be switching any time soon.

Regards.

I like godaddy, their coupons keep me coming back!

Godaddy is at the top.

I prefer Name.com .
also use Bigrock sometimes.

I find godady a great domain registrar they are fast with registrations and not too costly. also i have heard that enom are great too but i have no personal experience with them. hope this post helps.

Godaddy and ENOM are the largest, but we use Namecheap, they have been great for us =)

Resellerclub.com is very popular name in India as a domain name registrar they do also have wide range of TLDs available with them to register.

We like NetEarthOne. Very fast on answering support tickets and very professional. They do not try to upsell services unlike GoDaddy.

Definately recommend then if you want to resell domains.