In my view, I don’t think there is a single answer to the question. Some important factors to take into account include:
- The border crossings you are concerned about (entering the EU? reentering the USA? using a transit visa? etc).
- The basis for your concerns (are you an activist? do you plan to proselytize? are you a journalist? etc).
- Reasons, if any, border guards and immigration officials would want to question you (associations with NGOs, prior behavior, past destinations, demographics, etc).
- The purpose and format of your trip (business, tourism, group tour, individual travel, etc)
Personally, if I decided I was going to be at risk for either hostile border inspections or having my devices infected while abroad, I would use a burner phone. The hassle of preparing and restoring my “real” phone combined with the potential for something compromising turning up anyway during a search makes a burner my preferred option.
And one more thing™: here are two recent threads with related comments: