For me I'll choose the nucleus why? The nucleus controls and regulates the activities of the cell (e.g., growth and metabolism) and carries the genes, structures that contain the hereditary information.
The similarities of the sporophyte and gametophyte that they have related to each other is they are part in producing of plants as well if it is angiosperm or gymnosperm. The difference is sporophytes can only produce spores as well gametophyte can produce gametes( sex cells ).
- Just Don't Judge