I played Superstar Saga, PiT, TTYD, and heard some music from Seven Stars and know the basics of how they all play. Superstar Saga had some comical personality but it was more minor compared to the Mother series, the exploration was a mix of 3D and 2D (mostly 3D) with a few platforming elements in it that made it neat. And the battles were surprisingly really fun, involving timing to dodge attacks and timing to deal attacks. Very unique yet very Mario.
PiT had a little bit easier story to follow rather than being a "missionary" for the Beanbean Kingdom you went around the hubworld of Peach's castle going back in time to various places to collect, get this, more pieces to stars, but now the battles and navigation were a little more involved with babies involved. Much like the first title, yet in my opinion even better than it. Also less minigame type deals to deal with than SS. Oh yeah and there's two screens when fighting.
TTYD was truly leaning to a more RPG based type of gameplay but still with paper changing elements (where you can't really dodge attacks but you can defend from them, Earthbound elements (minor ones like the cricket hammer sound effect and Hooktail), still some hilarious text to read, some "missionary" stuff to do for the town for completionists out there, a "Pokedex" element, and some awesome music. And get this more star collecting.
My favorite would have to be TTYD. [yelling moving text effect] RRRRRRRRRRAAAAAAAAAAAAAAAWWWWWWWWWWWWWWWKKKKKKKKK!!!!! [/yelling moving text effect]