I believe an availability of resource throughout the surface is going to determine which solution is viable. Anything that requires some obscure resource availa

I believe an availability of resource throughout the surface is going to determine which solution is viable. Anything that requires some obscure resource available in a remote, difficult to reach location is going to loose unless it provides substantial benefits. You can already extract oxygen from CO2 or rock. Both are available everywhere and are trivial to reach. You only need energy (to heat it up) which can be provided by solar arrays -- renewable resource and the process to extract is fairly simple (heat it up enough and it gives out oxygen, basically). Maybe not that important, but both are also available in practically unlimited supply.