Most of them offer automatic renewals--they love customers that click automatic renewals. Godaddy literally changes your setting to automatic renewal.(This would be a good class action lawsuit--for such a classy company?)
The problem with automatic renewals is its fine if you just have one domain. If you have a lot of domains it makes financial sense to shop around? I've always gone with the cheapest registrar(that I feel will be around in a year, or two), and never had a problem. Personally, I heard a long time ago the true cost of registering a domain is around $7.49. I don't know if that's correct? I don't like to pay much more than that per year--just on principal.
Since, people are throwing around companies, Google domains are $10 bucks a year/with free privacy. (At least they were a few months ago?) Godaddy did away with renewal discount codes; I see no reason to use that company anymore?