In my personal experience, the estates that have the most difficulty are the ones where the parties don’t get along. Even if everything is being managed perfectly and properly, personal conflict will lead one party to hire their own lawyer, and sometimes even to start a lawsuit against the estate. Sometimes this even happens between executors who can’t get along. It wastes a huge amount of time and money that should be going through the estate to the beneficiaries.
The best advice that I can give if you must choose more than executor one is to choose executors who will get along, and to tell your beneficiaries ahead of time what your plans are. Processing it all now means fewer problems down the road.