I like them all but look forward to the Pride and Bushido PPVs the most. I like the production of their shows the best. They often have elaborate stages and put alot of money and effort in their shows. They have more top international fighters similar to K-1. They have multiple olympic gold medalists. Their crowds are very respectful and you never hear booing when the fight hits the ground too long or there is a stalemate.
There are good and bad with every organization. I just prefer Pride. I watch all the UFCs too though and I am a big fan of both. I also enjoy the WEC fights on HDNet. They have some entertaining free events. Plus it's in HD, so that's always nice.