New player needs Advice- transition from Jax

I need help. I've gotten to the point where i hold my own with Jax, often leading my team in turret destroys snd staying a little above one to one on kills to deaths. However i see all these mages that end up 24-1 and such ridiculous scores. I would like to switch to a good mage. does anyone transition well from Jax or just some good mages in general. Thanks!