Series? Tiga. Dyna too. I watched 1 and 2 of Gaia, but I'm busy, so until translations arrive in a few months, I'll wait.
I started my journey into Henshin Hero tokusatsu because of Tiga. It's a great show. Dyna is not as popular, but it also is good. It has more comedy, but it gets serious when it gets serious. In fact, one of the greatest episodes I've ever seen in tokusatsu or in anything comes from Dyna. It most likely will be my first post of official translations because I like it so much.