I will pitch this idea over and over until I die. Galio is where it's at.
. He has limitations, of course, but I'm riding his back out of Bronze at the moment, and it's a fun ride. He does massive damage if you build him as an AP mage (I'm consistently the highest source of damage on either team when I play him in ideal settings). If you need a tank, it's easy to build him as a tank because his abilities scale well on their own so farming and surviving is easy even with a full tank build. I build him as a tank against heavy-AD teams and the general softness of the AD champ build makes them still vulnerable to my damage.
But the biggest bonus he brings is his AoE 2-second taunt. Even without a single extra AP, it will do over 500 magic damage to anyone caught in it (before resists and if it's fully wound up). More than the damage, though, the taunt duration allows you to instantly turn the tide of a team fight and send the other team running.