We had similar discussions on this in these threads
- VV and VH Polarization
- Water threslold
- Difference between VH and VV polarization
- Use of VV & VH polarisations for Water Detection
Generally speaking, VV is more sentitive to vertical structures and HH to horizontal structures. This can make a difference if the water bodies are roughed by wind, have systematic waves or if there is flooded vegetation. But if VV is all you have (with Sentinel-1) you can give it a try.