I would personally say the British Empire as the Roman Empire contributed very little to the world beyond spreading Christianity.
The Romans are responsible, historically speaking, for the development of lasagna, chicken parm, Buffalo wings, fettuccine alfredo, calzones, Italian beef, and Chicago-style pizza. That is contributing very much to the world. The British, on the other hand, are responsible for "haggis" and "jellied eels" and something called "f****ts." Choice here is obvious imo
EDIT: tikka masala is good, rare W for the British Empire there