I don’t want to start another discussion about connections servers, etc. I would just want method to be sure that player won’t end on server that’s not convenient to him.
It can be done very simple:
[ ]RU
[ ]EU
[ ]NA
[ ]SEA
[ ]ANY
Just tick the box and this server will be included in search.
I would leave the option to select preferred server as well. In this case the preferred server will be selected if there are multiple games available.