Big difference that I have noticed between the 2, is that UA partner awards generally require 2 awards if not traveling to the home country. To travel to/from scotland to US, one needs an award to germany, then another award to scotland/USA. SO LH award would be 70K, wheras AA would be 40 or 60 depending on season. Could be crucial for scotland, since I don't belive UA flies there. Also AA awards let you combine transatlantic carriers, UA doesn't. This gives AA awards much more availability if you are flexible. I personally find AA service much better, but that's just my opinion.