For characters I feel like most of the iconic G1 characters have already been indicted. So my choices are from my favourite era of transformers, the beast era.
Optimus Primal deserves a spot in the HOF after everything he achieved over beast wars and beast machines. Having been thrust into the role of leadership and taking on a charismatic tyrant like megatron he not only saved Cybertron from Megatron's rule but saved he Optimus Prime and the fabric of time itself. Not to mention bringing about a new techno-organic age to Cybertron.
Then there's Rattrap just as a character I like (and my first toy) plus playing roles in the beast era and now also IDW he deserves a spot.

For humans
David Kaye: being one of the only people to have played both an Optimus and a Megatron and also providing several popular character voices (like lugnut for example) he deserves a spot. And clearly he loves having played Megatron. Why else would he record megatron Christmas carols every year?
James Roberts: for being the mastermind writer of some of the most popular pieces of transformers fiction ever (LSotW and MTMTE)
And a posthumous spot for Leonard Nimoy