Namecheap haven't got coupons for renewals so it's more expensive.
Namecheap have sometimes technical issues, but I like their domain management.
I would go for moniker - secure, cheap,have marketplace
You might use godaddy, depends what TLD type is cheaper with coupons.
My domain registrar comparison:
http://www.webmasterinter.net/category/domain-registrar-comparison
Enjoy.