A wise man said: Only invest 10% of your total capital into one project!
Great advice provided that you got enough capital so that your 10% can actually secure some property for you.
With Ajman you need to take few things in consideration:
Emerging market - high risks.
There is no infrastructure, lots of projects are launched but no one can tell when and how will they realise. Take a look at Dubai. Though its much ahead of Ajman in all regards, most of the projects get seriously delayed because the master developer is not ready to release the land to end developers. They struggle with infrastructure.
Try to get Ajmans master plan. Inquire about water and electricity supply for all these launched developments. You will not get very helpful answers.
Also, Ajman is living on a premise of all the people who cant afford to live in Dubai moving to Ajman. That might well be so, but it doesn't have to be. So again, the market is being driven by speculators who are hoping for 'new Dubai opportunity' in Ajman. Consider that Dubai is to greater extend driven by speculators, though the end users are more tangible then in Ajman. What you have now is the market in Ajman being driven by speculators who are investing on the premise of Dubai speculation becoming true. There are too many variables here.
In terms of rental income on the top of capital appreciation - the only place where you can surely count on that is Dubai - if you buy property nearing the handover. We can see from history that projects appreciate well near the completion, and generally there are no significant delays during that time.
If you are buying a finished property, you can see what you are getting, you can see the history of rental income and you can easily get mortgage thus enabling you to diversify your investment and maximise your returns by
leveraging. Though many people will say that the appreciation on completed properties is not as great as with off-plans, that can be made up for through easier financing as mentioned above, with much lower risks.
As you said, it's your hard earned money.
Back to DAYFox's wise man advice:
I would put 10% of my total capital in Ajman, 20% in RAK, and 70% in Dubai (on carefully selected projects).
Hope this helps.