I fly to/from the US 2-3 times a year and the coice of airline is, for me, dependant on the departure airport.
West coast US, first choice every time is NZ, no hesitation, unbeatable.
I will then look at AC as a transit point as their C is also flatbed, service is good and you can use the arrivals lounge for a shower if your final arrival point is LHR.
Next choice is LX only if I can get their new 333 service in J or any aircraft in F. 333 service limited to east coast and sometimes ORD.
Next choice in new UA C in their 763, limited to some LHR- IAD and ORD and one SFO-LHR 772 is now converted.
My views are completely biased towards flat bed as opposed to angled flat which is why I do not advocate LH, US, OS or CO. At the end of the day its very much down to your preferences.