There are just too many countries for me to list in any meaningful way, though I'll try to answer as best I can.
I'm a believer in supporting the home turf, and this puts Ontario in my #1 spot. And, I'm well known for voicing support for viticulture all across the North American heartland where grapes other than vinifera actually thrive best in the generally continental climate.
I've always love South African wines - especially Pinotage, but not just Pinotage - and this admiration continues to this day. Of course, I've had a good number of low-end duds from SA, though surprisingly the KWV wines, which have disappeared from the LCBO somewhat inexplicably, were never among the duds. It may have been a government cooperative, but KWV really made good inexpensive wines all across the board. I can't say the same for the many replacements that followed it.
France - I have come to love the French attitude towards food and wine, and the precision with which the French view the wine-terroir connection. I am slowly studying this great vinous nation's wines, but so far know that my favourites are Madiran followed by the Rhones. I still have Loire Sauvignon Blanc to study.
I tend to prefer northern Italian reds to those from the south of Italy, with the exception of the occasional Primitivo di Manduria.
Austria has long held a place in my vinous heart for its GV, Blaufränkisch and Zweigelt - fantastically food-friendly stuff.
And, of course, I hope for the day when Eastern Europe will start making serious reds from its many native vinifera varieties to counter the massive wave of international varieties and offer more diversity from a part of the world that has known wine for a very long time but is suffering from the effects of the post-Communist maelström.