I unfortunately have not gotten to review the DVD's by Joanne Ross but I have seen the Patty Cloke ones. I think it really depends on what you are planning on using your horse for. If you want to compete in AMHA/AMHR shows then use the Patty Cloke videos. If you want to produce a safe driving horse for going down the road or doing carriage driving competitions then I'd pick up Clay Maier's "Training Your Horse to Drive" DVD set. There really is quite a difference in approach depending on what you're training for.
Leia
Edited to add: Of course, that's for training your HORSE to drive. If you need to learn to drive, go get some lessons! There is absolutely no substitute for learning under an experienced driver. Remember that green plus green equals black and blue...you have to know what you're doing before you can teach the horse.