For sake of the 'LH is cr@p I'll fly others instead' argument

Interesting terms on the BA website: https://www.britishairways.com/trave...n/public/en_gb
The main bag is dimensioned slightly bigger than LH (maybe the overhead bins in A32S are from a different supplier) and a note that the laptop/handbag must go under the seat in front of you.

AB: one piece same size, same weight http://www.airberlin.com/site/flug_g...eu#handgepaeck

AF: similar dimensions, weight incl the small undefined bag http://www.airfrance.de/DE/en/common..._airfrance.htm

KL: similar to AF http://www.klm.com/travel/us_en/prep...gage/index.htm

The 'best best best' SQ is 7 KG: http://www.singaporeair.com/saa/en_U...v=-1300065563&

The cool EK is between BA and SQ: http://www.emirates.com/de/english/p...age_rules.aspx

The american carriers seem to be of comparable size:
UA has the same dimensions, no mention of weight: http://www.united.com/page/article/0,6867,1032,00.html

AA has the same size as LH, no weight mention, laptop bag has to go under the seat: http://www.aa.com/i18n/travelInforma...false&from=Nav

DL: same dimensions, carryon costs if checked at gate: http://www.delta.com/traveling_check...ryon/index.jsp