Kindle 3 / 3G offers free internet access, as you state, at least in some countries (except Germany
All later Kindles (Kindle Touch and Kindle Paperwhite) only give you access to Amazon shop and Wikipedia.
Reading about the Touch and the Paperwhite issues, I would rather stick with my Kindle 3 / 3G (called Keyboard now). It is available in Germany at t much lower price than when it came out.
I use the Kindle 4 (NT) for conmuting since it is smaller and lighter. The display of the Kindle KB is so far the best, except for the new Kindle 4 Black (again cheaper than the original low price Kindle 4 NT).