He two questions you need to answer first are:
A) how long do you plan on staying there?
B) do you plan on brewing for a long time.
If the answer to these are yes, go as big as you can220k-600k burners to allow for future expansion. The other nice thing is even going electric, you always have the burner as a back up and if a point in time the size of your batches becomes large enough that you need to run additional 220 lines or your electrical panel runs out of space you have the burner there already to transition to.