My experience, First class Cape Town to Manchester return in Dec/Jan.

EK773 Dep CPT 13.10 arr DXB 00.25 about 9 hours - amenity bag, pyjamas and slippers
EK017 Dep DXB 07.15 arr MAN 11.20 about 7 hours - amenity bag and slippers
EK018 Dep MAN 13.10 arr DXB 00.25 - amenity bag and slippers
EK770 Dep DXB 08.55 arr CPT 16.30 - amenity bag, pyjamas and slippers

I didn't notice any difference between business and first class bags. I think they look and feel cheap.

On all legs we also got a 2019 diary and pen!