It's totally fine to play with the methods to prioritize. This is especially true when you have a big amount of ideas. When this is the case I personally mix the methods like this:
- Affinity sorting: in order to clear the mess into categories and have the same ideas stacked together
- Dot voting: to get the top 20-30 of the best ideas
- Impact versus Effort Matrix: to see which one we should pursue
At each prioritization stage I take a photo of the result to document the process in case decision makers who weren't there need to understand the process.