Honestly, I'd quite like a nobody actor who just is really good. There is such appalling nepotism among already rich has-beens like Fry.
JKR has been quite good at promoting those without power/ money but with talent in the past. Her name sells so it needn't be a big name and there's a huge number of women and children who'd absolutely love to be able to listen to the HP books without also having to listen to Fry's smug misogynistic tones (just read the Glosswitch article and yes - his female voices are steeped in misogyny - one of those things I won't now be able to ignore).
If it has to be a 'name' I'd like Hugh Fraser as have been enjoying listening to his narration of some Christie classics. He has a lovely voice. He is 79, but if he's willing then I'd quite like him. And this has made me think of David Suchet who is a great character actor and does women's voices better than most male actors - though it's hard for anyone of the male sex to very convincingly portray women's voices in my experience. We don't just see sex, we hear it too.
It'd be nice to have a woman reading them- but I can't think of any female voice actors who I've enjoyed listening to as much as HF when I listen to audiobooks.