Ok, that all explains why I can't just find a canonical list. I figured it wouldn't be as easy as 'Emirates has 3 classes', but more like 'Emirates has 3 classes on EK001 flying the DXB-LHR route during the summer except at weekends'.

For context, for my last trip, I found that eco+ on Qantas was comparable in price to eco/bus on Emirates. I wouldn't have been able to do eco/bus on Qantas because of that eco+ class, but it was pure accident that I came across the Emirates price because they wouldn't have been an airline with which I'm familiar.

I just need to be more aware of these options when booking long haul