For the English supporter, this is a tough call... who do we want to win? Whenever I've asked someone today who they'd prefer to win, the answer has been 'neither'!
We have a history with both (both on and off the field), so we can't just look at that. I think I'd prefer Germany to win, as assuming that England get through (not a safe bet in my opinion), a final against Germany would be preferable to one against Argentina. This is because Argentina have looked the stronger team, and playing Germany at home (and hopefully beating them) would be sweet.
Admittedly, there's another match before the final, so it's possible both could get knocked out.
... and there are still two major obstacles before England has a chance at seeing the final. If we survive Portugal, the last obstacle is Brazil - although admittedly they're no longer as formidable as they once were, they're still fairly scary.
The laws of narrative suggest that an England/Germany final in Germany would be a good end to this world cup. 40 year of hurt and all that. Does the real world run on narrative?