[[!FormItCountryOptions? &selected=`[[+fi.country]]` &prioritized=`US,GB,DE,RU,JP,FR,NL,CA,AU,UA`]]
You can use the prioritized property to select a list of countries that will be displayed at the top of the list:
[[!FormItCountryOptions? &selected=`[[+fi.country]]` &prioritized=`US,GB,DE,RU,JP,FR,NL,CA,AU,UA`]]