With Enom or Resellerclub/Directi you can customize your site and you handle your own customers. With GoDaddy/Wild West you get a template site, GoDaddy handles customer service and billing, and you are essentially a pass-thru affiliate. Depends how hands on you want to be and if you have dreams of going more independent. Most resellers do little real 'reselling' and use the reseller account to handle their own portfolio at reseller prices. Domain reselling is a low margin business and you need huge volume to make any real money. At $1-2 dollars profit per domain I don't think the customer service headaches are worth it - in that case GoDaddy's program has advantages - take the commission & let them provide the support. Either way it's better to combine the domain registration business with webhosting which is way more lucrative. You can be a webhost reseller, affiliate, or start your own.
I did tons of research on this not to long ago... If you want to become icann its not worth it unless you have big plans and a large marketing budget.. I recommend resellerclub.com for the best reseller program.. Other programs are not as good. PM if you need help I am not a part of any reseller group etc.. just willing to help out =)