the best coverage depends upon where you live. different carriers are better than others in different areas.
the best value is with sprint. the 'any mobile any time' plan for $69.99 includes unlimited internet, data, texts and is the best value in the industry.
the best phones depends on what kind of phone you want. outside of the iphone, i think that sprint has the best phone line up b/c they have something for everyone and have several free phones.