My preference is

I think .ca names the best for investment percentage wise. You still register pretty good names that will bring you 300% percent guaranteed during next 2 years

I personally think that .IN (country code for India) has potential ,Reasons for my view? (1) wide use of English; (2) growing economy and large proportion of tech savvy; (3) clear rules on access to registration and selling by folks outside the country; and (4) nice, short, pronounceable extension.

.com is leading from all extension.

.com could never be replaced as it is branded as the default internet address extension around the world. If you are using another extension other then .com, no matter how much you spend on branding your address with your extension, you will still be loosing visitors if you do not have the .com version.

As a traffic collector/seller I dont care about .ext and I register any extension domains which can bring traffic/revenue. So some predictions about possible traffic/revenue a domain can give are more important for me than just investing in .ext itself.

.com is a good investment obviously.

After .com .cn and .in are also excellent investments considering their 1 billion+ populations each and the number of people using the internet in each of those countries is rising rapidly. I think .cc is one of the worst investments and the more extensions that come out the more it will decrease its value.

I find .com is the most valuable TLD. I think no one can really doubt that.