Thomas Radzinsky chose Club before country. At that time he was playing the second round of the CL with Anderlecht, and stopped playing for the Canadian team.
I guess it all depends of the level. it's not worth to risk your big club carreer with matches in a Crappy NT.
But then again, if you're brazilian, argentinian, italian,... it's wonderful to wear your national jersey.
If I really had to choose, I think I'd go for Country. winning the world cup, is I think the greatest dream for any football player