Edit1: The reason i was thinking 30a/250v is so I would be able to take the system with us if we move years down the road - easy connection to a dryer outlet.
If and when you move, are you likely to pick a house less conducive to your hobby? True, using any standard dryer outlet would be convenient, but brewing next to your dryer might not be. If you have such an eye towards your brewing habits at this house and at this stage, I would think future houses will only be more customizable towards brewing.
The wire is the cheapest part of your decision. Breakers/GFIs, outlets, and plugs are where the price rises as you incress your amperage. Consider running 6 AWG wire, because that is the hard and semi-permanent part. You can still size everything else at 30 AMP, but you could then very easily upgrade to 50 amps in the future. Just saying--what is hardwired in your house is the hard part to change. Swapping out breakers or outlets can be done by anyone. I am running a dedicated 60 amp GFI to a 60 amp outlet. From their I have a 60 amp plug on 4AWG wire going into my panel. From their I can accomplish nearly anything I want.