Avoid LHR if at all possible. In the past 6 months it has gone from one of the easiest connections in Europe to one of the worst. If you are traveling with a knapsack and a computer bag, be prepared to figure out how to get two pieces of luggage to look like one because you will NOT get past security with 2 pieces.

If ZRH or even FRA are options, I'd definitely go with one of them. It would take some serious money and/or scheduling advantage to make me use LHR as a transfer point.

DF