Not the yen, or the euro or the reminbi. Sure as shootin’ not the U.S. Dollar or the pound.

Yep, it’s the Loonie, Canada’s dollar with the ghostly-voiced diving bird on it, that gets my vote as the world’s greatest currency. And not just at the moment either. This is the currency I most want to own for the next decade.

Right now, all the currencies of the global commodity producers are in rally mode. The Australian and New Zealand dollars, the Norwegian krone, and the Canadian Loonie have all hit 11-month highs against the U.S. dollar this week.

You don’t exactly have to be Mycroft Holmes to figure out why. With a belief that China has gone on a sustainable commodity buying spree to support its economic recovery, commodity prices have soared and so have the stock markets and currencies of countries with commodity-based economies.

 The iShares MSCI Canada Index (EWC) is up 80 from its March 9 low through the close on August 5–the U.S. Standard & Poor’s 500 Stock Index is up 48% in that period–and the Canadian dollar is up 21% against the U.S. dollar during the same time.

I’d put the Canadian Loonie and Canadian stocks ahead of the currencies and stocks of other commodity-based countries because Canada’s commodity basket is the most diversified in the world. (Well, Brazil will give Canada a run for the money on that standard if the South Atlantic oil discoveries pan out.) Canada has Norway’s oil, and Australia’s mines and farms, and New Zealand’s timber and farms all in one package.

And Canada’s Loonie is better positioned in the interest rate cycle. High domestic interest rates–as long as they’re not so high that they signal some major economic dysfunction–add strength to a currency. Part of the strength of the Australian and New Zealand dollars, for example, results from the high 3% and 2.5% interest rates, respectively, set by the central banks of those countries. Money flows into Australia and New Zealand as investors look for those higher yields and that pushes up demand for those currencies (since to get the yield you have to buy something denominated in the local currency.)

Canada’s Loonie is as strong as it is even though the Bank of Canada has set its target interest rates at just 0.25%, exactly what they are in the United States. That means there’s plenty of support in the wings for the Loonie when the Bank of Canada eventually–no sooner than the middle of 2010, the bank has said–starts to raise rates again.

And the Bank of Canada has indicated that it’s not about to muck around in the currency markets anytime soon. That’s always a worry when an exporting nation starts to get hammered by declines in its exports due to an increasingly expensive currency. The fear is that the Bank of Canada would do something to weaken the Loonie and make Canadian exports more attractive to overseas, non-Loonie buyers. But the bank has repeatedly said that it will keep its hands off the currency unless its outlook on growth and inflation materially change.

But finally, the reason that I prefer the Loonie to rest of the world’s currencies, and certainly to the U.S.dollar, is that Canada is a country where the accumulated national debt has been falling–and not climbing for most of the last decade. After hitting a high near 80% of the country’s GDP in 1995-2000, Canada’s accumulated national government deficit–you know that thing that gets larger and larger in the U.S. every year and that we’re hoping our children can figure out how to pay–has dropped pretty much year in and year out until it stood at just 30% of GDP in 2008.

In comparison, the U.S. ended 2008 with an accumulated federal debt of about 70% of GDP.

Both countries have gone to the debt well in the current Great Recession. Canada will show its first budge deficit in 11 years in its 2009 fiscal year. As a result of its own stimulus spending and falling tax revenues with a slower economy, economists forecast that the country will run a deficit of $CDN 64 billion over the next two years. Canada isn’t likely to see another budget surplus until 2014.

If only the U.S. was looking at nothing worse than that. However… The U.S.budget deficit for fiscal 2009 will be something like $1.7 trillion. And the red ink stretches as far as the eye can see. Listen carefully when a U.S.politician talks about fiscal responsibility: all they promise is to reduce the size of the annual deficit, eventually.

Nobody is talking about actually reducing the size of the accumulated deficit. The relatively optimistic forecasts from the Congressional Budget Office say annual deficits will decline to just 2% of GDP by 2012 and then stay flat at that level until 2019.

And the accumulated federal deficit. Well, it will break the old record of 108.6% of GDP set in 1946 (Great Depression plus World War II) by about 2025. But unlike 1946, the ratio of debt to GDP won’t start to fall after it hits that mark. It just keeps on climbing.

The U.S. isn’t unique in facing this fiscal disaster. Things are worse in the United Kingdom, Japan, Italy, and most of the developed world and much of the developing world.

It’s Canada that’s unique in its relative fiscal soundness. You should put some money north of the border.

In my 10:30 post I’m going to give you the name of eight Canadian stocks to buy if you find this scenario convincing. Not right now. I think we’re getting closer and closer every day to a correction that should give you a chance to get in at a better price. So wait. But this is a long-term trend that you’d like to see on your side.

(Come to think of it, it’s one of the long-term trends in my book The Jubak Picks.)