Bristol Ground school all the way. Their reputation is built on years of constant top results which gets better all the time. Im an average guy with no A-levels or degrees and i had my Mod 2 results yesterday and averaged 98%!! Thats all 14 passed 1st time with a 96% average. There is no way in the world i could of done this without Bristol and the study manuals.
Good luck who ever you choose.