You'll likely soon find it's not all it's cracked up to be, even with the power you get from it.
The Chosen Ones are the only people who can touch the Gem and unlock its full power (though what this actually entails has never been fully explained). Their identities change as the "plot" progresses. As revealed by the Convenient Plot Device at the close of DYOS X, the current ones are choxorn and taillesskangaru.
The Defender of the Universe is tasked with guarding the Chosen Ones.
The definition of a "Chosen One" has always been somewhat obscure, with multiple, sometimes conflicting, interpretations. The identities of the Chosen are determined by the Gem, or, rather, by whomever or whatever created the Gem and "programmed" its rules. The Chosen Ones were initially believed to be DYOS contributors "important to the plot", and must 1. not be an evil villain, 2. not be likely to abuse the Gem's power and 3. be alive. According to further revelations, the Chosen Ones are more simply "incorruptible" individuals. The identity of the Chosen Ones will change if they no longer fulfil these and other secret requirements. There are always two at a time, and only both working together can harness the Gem's full potential.
At the start of the Avatar Wars, the Chosen Ones were Judge_Deadd and e350tb. kulade knew this, and hoped that by killing them he would gain their powers. His avatar minions were sent to do the dirty work, and the identities of the Chosen One shifted - though not to kulade as he expected, but to choxorn and taillesskangaru. kulade was only told later that he needed the Chosen Ones alive, but never got to know the identities of the new Chosen Ones.
Although lord_joakim touched the Gem and lived in the middle of DYOS X, he is not a Chosen One; he was left with mutilated hands and caused some weird stuff to happen. It is currently unknown whether the Gem can rectify his situation.