I'm not sure that I'd reccomend Griffiths for actually learning E&M, I worked through it okay but there were certain sections which I only understood because I already had a solid grounding in the core concepts behind E&M.
It is fairly good at doing what its supposed to, though, and that's taking people who already know some E&M (i.e. Physics Juniors) and teaching them how to deal with much more complicated situations than those which are covered in the elementary courses.
The only text I have ever seen that could replace Jackson is Schwingers text on Electrodynamics. It hasn't gotten much press, it is well written and each chapter is short, very short and very intense but readable.....
Griffiths isn't the best undergrad text out there, Wangsness is.
Smythe is a very good text, not up to date, but if you can do those problems you're doing very well.
In my opinion, what makes a better E&M text really depends on what you want to learn from a course in E&M.
Do you want to solve boundary value problems for (say) a particle detector or a waveguide?
Do you want to determine trajectories of charged particles?
Do you want to learn about electrodynamic effects in matter?
Do you want to learn a relativistic field theory?
Maybe a little bit of each?
Other intermediate/advanced "E&M texts" (other than Griffiths) might include Landau/Lifshitz, Ohanian, Lorrain/Corson.
An interesting text is by Ingarden/Jamiolkowski.
On a side note... will E&M texts ever emphasize more differential-forms and tensors, rather than just standard vector calculus? Certainly, there must have been an earlier "standard" text that didn't use vector calculus, and was eventually replaced by one that used "more modern methods".