I have been Jet Seal 109 on everything lately. Partly because it's cheap, effective and lasts ages. Though I really wan't to have a go with the G-Techniq range.
I have tried some of the G-Techniq range and thought it was really good. I have the C5 on my wheels, and it makes them really easy to clean, the dirt doesnt stick at all. Its pretty expensive, but so far I think it was worth it. Also, the I1 Smart Fabric spray is AMAZING!! You can spray it on fabric and it makes it completely water repellent. Not only is it brilliant fun to make random things around the house waterproof (the first thing we tested was a tissue - could run it under the tap and it was fine!), but it could also be useful for things like convertable roofs, seats and mats.