Neither aerator will do much to keep your filamentous algae suppressed because the primary nutrient source for your FA is the inflow water which is laden with dissolved nutrients. Those nutrients will grow some type of plant, that is what dissolved nutrients do. Surface disturbance from a fountain has minimal impact along the sides or edges in shallower water where FA thrives. I think the diffused air system will do a better job of reducing filamentous algae that grows due to the nutrients that are released / recycled from anoxic (oxygen starved) sediments which will be suppressed by a bottom aerator. But as I said your FA (at least early spring growths) are due primarily to dissolved nutrients from watershed water not from nutrient recycling from thermal stratificaion. No form of aeration suppresses nutrients entering a pond from runoff.
Don't bother switching the power to 220V unless your electrician says 220 on single phase runs cheaper the 110. An electrical engineer will also be able to verify this.
I don't think you should go out of your way to get a rocking piston compressor. Although it will work adequately in your situation, but if you can get a good deal on a rotary vane compressor based aerator system take it. I have had many GAST 1/4hp rotary vane compressor units running so far for 6-8 years with twice daily on/off cycles with no problems so far. If you have a good check valve system at the diffuser and you keep moisture away from the pump there is minimal effort on the compressor each time the system starts up. Moisture can cause problems with compressor start switches.
