Why ocean liners make the strongest hospital-ship conversions

Would a surviving British Empire choose a container ship, tanker, or ocean liner as the basis of a replacement hospital ship?

An ocean liner, because its existing accommodation and service systems are much closer to hospital requirements than those of cargo ships or tankers.

An ocean liner already contains cabins, kitchens, cleaning facilities, ventilation, and large public rooms that can become wards or operating spaces. Britannic supplies the historical example of adapting a passenger vessel for medical work. Existing corridors and accommodation also make it easier to separate staff from patients. A suitably sized container ship could accept modular hospital units, although the arrangement of its holds and decks matters. Cargo conversions require more new accommodation and services, while a liner begins with much of that infrastructure in place.