Champs & Boredom

I really love League. Awesome game but I have a problem with sticking with champs. I cannot find one champ to stick to. Within a week I become absolutely bored of a champ and pretty much never play it again. I really want to save up ip for runes. Any tips? Really fun champs to play?

Champs I like to play Riven Xin Xhao Udyr Kog Maw Swain