For long term registration, GoDaddy is typically cheaper whereas Namecheap prices are constant no matter how many years you register the domain name for. Namecheap however does not load you up which too much upsell of services and it is pleasant to work with. For me, the only choice between the two is Namecheap as GoDaddy does not permit my country, Singapore from signing up with them.
Something that not many people know about Namecheap is that even they started as a big enom reseller now they have their own accreditation license so as the owner said he has plans to give even lower pricing structure. Last time i had news from him was the time when they were creating their own accreditation software Namecheap can't be compared with GoDaddy Namecheap all the way... real registrar experience not a supermarket of related or non related services like GoDaddy does It will be no suprise to me if Mr.Parsons (GoDaddy's owner) starts sell souvenirs from the war he fought in Vietnam together with his domains I think people vote for GoDaddy here because they don't know/used before NameCheap