One advantage that I hope a paid version of GPT4 has (like ChatGPT Premium) over a free one (like Bing), is that it is a matter of time before the Bing answers will be polluted by whatever an advertiser is willing to spend its money on. Whereas with ChatGPT I am the paying customer.
I say "I hope", because time and time again it was shown that companies happily take money from both sides and skew the product to the wishes of the one that pays most, i.e. not me.
And since the results of AI are way less transparent than the appearance of an ad, the user will be screwed. If anything, GTP is a master of undetected product placement.
So in the end it will all be in vain, but for now, the paid version looks better than the free.