Since I'm only now fleshing out the Toa Team that I created eight years ago (never made MOCs of all of 'em, unfortunately), my current strongest characters are Jalon (my Self-MOC) and Artuhrenn (my brother's Self-MOC).
Jalon is the Toa of Time, with his masks including a Kualsi, a Matatu and the power of the Vahi. This gives him the ultimate repitoire of abilities: telekinesis (letting him move not only objects, but individual atoms, giving him the ability to create things made of plasma), quick-travel (self-explanatory), and control over time itself. Though he mainly uses his Vahi to slow down his perception of time around him, he can use it in conjunction with his other masks to fight in a precise, combo heavy and deadly style. He can also use it like a sort of Witch-Time which, if you've ever played Bayonetta or seen her in Smash Bros, triggers a counter after being attacked that slows down time for her opponents, allowing Bayonetta to set up epic combos. Besides this, Jalon can also time-travel, which comes in handy when observing the Great Beings and figuring out their next moves.
In comparison, Artuhrenn is the Toa of Space, with his mask being an Akaku. His spatial powers allow him to teleport, jump dimensions, make holes in the time-space continuum, and more or less tamper with the fabric of the multiverse, which is something Jalon tries to avoid if at all possible.
You can see why the two brothers don't get along.