It's worth saying that rankings group courses together, so it's quite possible for an average course to have a high ranking (if other courses in the institution are doing really well) and for amazing courses to have poor rankings. Once people know how the data is gathered and compiled, they don't tend to believe rankings quite so much.
Having said that, the courses you mention are all good. Kingston is fairly experimental in nature (in a good way!) and explores the boundaries of the subject much more than the other two, which might appeal to you or might not. Loughborough is a bit more academic in structure, from what i've seen. Portsmouth is a bit more traditional, with lots of students producing high-quality typography.
All three should give advice what they want in a portfolio. If not, just email the course leader.