BD is only easy in that they readily comp. In terms of actual earning, BD became far less generous last year when they 'enhanced' their programme and many discounted Y fares only earn 25% or 50% some even 0%! Having said that, if your flying J or F they are still a programme of choice especially if you are UK based and can get hold of their credit card (with it's 20K sign up bonus). If your down the back, your better off crediting to either UA, US or AC. Even LH is much better to credit to if your in discounted coach. LH's biggest issue is that you have to earn more miles to gain the same level of status, but their status does last 2 years so it evens out in the end.