Goodness me! (to be polite).
There may be one or two threads on this subject already. If not ten. Do a search my friend.
As said earlier, students only go to one provider, so even someone who has completed cannot answer your question.
That said, in a nutshell, I've not heard many bad things about any of the schools. Most seem to go to Bristol and they worked for me.
One thing which is a universally accepted is signing up to the Bristol online question bank. Almost madatory!
Probably best off choosing the one closest/most convienient for you.
EK