I'd go with the Han. Or maybe an old November.
In seriousness, I think the Virginia would be the best option. Having 20 years on the Akula design, they will give you more 'bang for your buck', as they will remain technologically competitive longer than any Cold War design.
I agree that there is nothing that can touch the SSN-21 class, but the US only built three of them If anyone needs a fleet, this is not an option.