First, which location is most similar to your climate? I live in a temperate region that really wants to be a forest. While I am super duper impressed with Geoff Lawton, his material is geared toward tropical regions. I can't count how many trees I got all excited about tree X... until realizing that they have no chance of surviving my winters. In my opinion, a PDC from him would be of less value to me than Paul's PDC.
How important is the PDC certificate to you. I think Paul's video PDC does not include the certificate. The course in person does include the certification.
Permaculture Education PDC 72-hours of video. This one has 15 members on their staff. The main two guys both trained at the Mollison Permaculture Research Institute. These two men each have 28 years of permaculture experience. This is according to their 'about page'. In the end, if you have completed the course and the design, you will have a PDC certification. Email access to questions answered by the staff. Does this perk end at the course completion? There is lifetime access to the course materials.
Paul's PDC and Appropriate Technology 177 hours of video instruction. As candy from supporting a previous Kickstarter, I have access to Tim Barker's PDC notes. The notes read like an entire very detailed book.. in need of a little editing. I refer back to it fairly often. There will be natural building included in the technology portion of the videos. Earnie and Erica Wisner teach about building rocket mass heaters. They have built a lot of them. Real experts on the subject. Then there is Paul Wheaton.
You will have lifetime access to Permies.com, where you can ask all your permaculture questions. If you choose the other PDC this access will be revoked. You will not be able to read Permies from any computer in the world.