Dan, that's a terrific question and no doubt a can of worms has just been opened for those of us who strive for a self-sufficient lifestyle.
Like many choices and decisions people make in life the type of self-sufficient lifestyle a person desires can be discussed in a general way and also in a very personal way. I can give you general advice about your list of "features" a perfect self-sufficient place should have and where I think the location in the world best fits this description; however, ultimately even if you have no experience at all in self-sufficiency, you'll still know better than me about what suits you. In other words, IMHO no one can tell you where the best place would be for you to set-up your own self-sufficient property and lifestyle.
Self sufficiency excites me 24/7, and I could talk till the cows come home about what my perceived best self-sufficient places would be but I don't think that would be fair to say one region is better than another. That's for you to decide based on your own personal circumstances, which does come down to: money; family; personal health; experience; perception of self-sufficiency;
extent of self-sufficiency; and many other motivating factors within and out of your control.
Having said all that, I'm going to have a go at answering your thread because it's very interesting and I'm sure we can all learn from discussing it. Firstly, you say you're
looking for a country to become self-sufficient but you're unsure which one to choose? What's wrong with your own country? I'd definitely start my search there first before considering moving countries - for obvious reasons. I believe there are few countries in the world where a self-sufficient lifestyle couldn't be achieved (mainly talking 1st World here).
Here's my attempt to answer your other criteria:
All climates have there plus and minuses but I would say it's easier to live a self-sufficient type lifestyle in a non-extreme climate. Places that are too hot or too cold with too much or too little rainfall, are tough places to live so somewhere around the middle like a temperate or sub-tropical climates might be better but some may disagree - please do
Find a property with perfect well draining crumbly volcanic soil with lots of organic matter which holds moisture then that's great! I live on heavy clay soil, so I just have to work harder to improve my earth before planting and growing or keeping animals.
You should be able to find a property on the fringes or outside of the cities with a clean water source - I'd be surprised if you can't. Drilling or buying a property with a bore (underground water) is always handy. So to, is living near a lake or river.
I'm not sure if you mean animals already on the land or a property best suited for animals; however, most poultry and domestic livestock do best with a grassed landscape for free ranging so that's what I would look for. This largely depends on your skills but assuming you have the skills to build your own home with wood from your property, then I would expect you'd need to buy farmland (rather then fringe acreage) and ensure the property has sufficient trees to meet your needs without damaging the environment. Plus, depending on where your live tree felling might be subject to approval.
This can be pretty subjective limited rules and goverment (I want to live off the grid without have to worry about rules about building you own house or rules about having animals or having to pay taxes and so on..)
Living off-grid can be done easy enough with solar and so can building your own home but living like "Grizzly Adams" is probably a little unrealistic. I have seen and visited people living like this in remote areas of Northern Australia when I worked for a liaison team in the military years ago - they are basically squatting on state land - but I wouldn't recommend it.
Cheap price for land Usually, the further out from the city you go in any economy the cheaper the price gets - it depends on how far away you are prepared to live from the urban centres.
I'd say, to find the "perfect self-sufficient property" in a first world country with hardly any restrictions at all from authorities would be quite a hard task - it's nice to dream though...
At the end of the day other people who read this thread may answer with their own helpful views and opinion (probably differing from mine). Some may name or have an exact place which they believe offers all those points you request but I hope I've helped a little... Personally, I love South East Queensland, Australia