I've seen all of Magiranger, Boukenger, and Gekiranger. While Magi is by far my favorite, Geki was just an amazing show. Jan (GekiRed) was pretty annoying in the beginning--I'm generally not a fan of the fiery-screaming-Red--but he got a lot better as the series progressed, and was less pissed-off than he was happy-go-lucky. Geki is really all about the villains though; Rio and Mele trounce every one of the rangers.
As for Go-Onger, I've seen what T-N's subbed, but to be honest, I'm not really getting into it as much as I want to. I'm always prepared to give a new iteration of the series the benefit of the doubt, but Go-Onger's characters just aren't doing it for me. I'll stick with it for a while and see how it turns out.
As for Kamen Rider: that series is always hit and miss for me. I tried watching Ryuki and Blade and couldn't get past the first few episodes of either one, but I ended up marathoning Kabuto. Den-O I dropped after a few episodes, but I'm sticking with Kiva right now. The dual-timeline storyline is pretty interesting, but to be honest, I'm mainly watching it for Nana Yanagisawa, who plays Megumi.