While you can use the miles you accumulate for upgrades and award tickets on any *A carrier, there are other perks of status that you get only on the airline where you have your FFP membership, such as upgrade priority and treatment during IRROPs. Therefore, I would lean toward the program of the airline you will fly the most, or with the airline you will fly most often internationally. In your case, that looks to be LH or UA. It is true that LH has a high requirement for gold, but your gold status with them is good for two years. Plus, once you hit silver with LH, you earn 25% bonus equity miles so next year you only need 80,000 miles for gold. With UA, you only need 50,000 miles for gold, but the real benefits kick in at 1K, which requires 100,000 miles.

So if you don't think you can make 100,000 miles, I would suggest UA's program; otherwise, I'd go with LH's.