I have a GoDaddy reseller package, so can comment on the pros and cons of that:
Pros-
-cheaper registration for yourself
-you get a cut of all sales (you set prices within a realistic min./max. range)
-relatively cheap and easy to get started
-GD provide all the technology and accept the creditcard/paypal payments for you
-GD handle customer service (unless you choose them not to)
-you can actually undercut GoDaddy without coupons (I just use my own reseller account for $6.95 .coms without looking for a GD coupon)
Cons-
-GD charge an annual fee to be a reseller (although 'Super Resellers' are able to offer the reseller packages at a discount- for example see my
dnReseller.biz where GD's $99.99 reseller is only $60pa)
-Ugly interface (much like the GD homepage)
-Difficult to customise
I've not used any others yet, but am considering one of the (more expensive) eNom reseller packages, I'm sure other members can provide info on the pros and cons of the eNom/DirectI packages (which I'd also be interested to hear opinions on).