Haven't tried campaign monitor. As for Mail Chimp, I like it very much. Loads of intergrations lately with other services, if that is any useful to you. Also like the easy calls to action for social media outlets (e.g. Tweet this). Pricing is reasonable. Embedable forms are OK. If you need a pop up sign up form you won't get it (for the moment), I've tried AWeber for that.
Stats are very good and they have an "inbox inspection" feature which lets you correct possible errors before sending out the campaign.