Well "easiest" for TATL without a doubt is BA (which can also be obtained with AA miles). Their J award inventory is plentiful (tons of US destinations and I think they guarantee at least 2 award seats on every flight when it opens up for booking to offset their latest devaluation) but you'll be hit with high fuel surcharges.

UA and AC are pretty good options to get *A TATL flights. UA charges 140k for partners and 125 for UA metal but no fuel surcharges. AC charges 110k or 115k depending on where in Europe you are going but passes on fuel surcharges where applicable. For both, LH is a good option, they often release J and F space at T-14.

Based on your profile which says AMEX, your best bet is AC. FlyingBlue (Air France/KLM) is also a decent option at 125k and is a transfer partner but only if you are leaving from a city served by AF/KLM - otherwise good luck finding DL saver Y/F to connect to the AF/KLM flight.