The executor of your Will and the Agent under your Power of Attorney perform two very different functions, though many people do get them confused. 

It may help to keep them straight if you understand that your Will only operates after your death while your Power of Attorney only operates while you are living, but stops working at the time of your death.

Therefore, you should select an Agent to act under your Power of Attorney who you would want making financial and legal decisions for you during your lifetime, in the event that you are unable to make your own financial and legal decisions due to an incapacity.

The person you select as the executor of your Will is the person who will take care of things after your death and will be responsible for ensuring the distribution of your assets to your heirs or chosen beneficiaries. 

In most cases, these two roles can be filled by the same person.  But, in some cases you may want one person to take care of things for you during your life, but would want someone else to handle things for your heirs after your death.

In any event, the person or people acting in these roles should be someone you absolutely, totally 100% trust.  Other characteristics to look for in these roles is someone who has great common sense, strong organizational skills and will take guidance from your trusted family lawyer rather than thinking they should and could do it all alone without professional advice.