Best mileage accural, if you're flying paid Business (or higher), are bmi's Diamond Club, and Lufthansa's Miles & More.

LH offers 2X miles for most business class fares and 3X for first. Taxes on awards are high though.

bmi 2X miles for business (1.5 for AC/SQ/SA), and 3X miles for first. But after gold requalification, bmi's accural can up to 4.25X miles for business and 6.25X miles for first. bmi offers one way awards and a 'cash & points' option. Fuel surcharges and taxes are also high on BD, but if you collect on AC you're already used to that.

UA's program benefits the Economy or Upgraded customer. Mileage accural on UA favours flying only UA metal, offering 100% bonus miles on UA flights and LH codeshares TO USA (similar to AC's bonus on AC only metal)

SQ PPS is not part of their mileage program, but a set of loyalty levels based on paid business and first on SQ flights only. You can collect PPS credit even if you award points to another program. Miles can be collected in any Star Alliance member, and PPS credit can be registered simultaneously. The flight must be a SQ operated and SQ ticketed flight (codeshares do not count).