So, basically you're looking to lower your 30% WHT tax on dividends. For that you need to find countries that have good DTT with US and also to check if the dividends will be taxed as PT (not really sure about this part - would like if someone knows more to write about it).
So, as far as I know the lowest WHT options (also mentioned here above) are Romania and China (and Russia) at 10%.
Romania could be the great choice (low cost of living, big country, EU state, etc).
At 15% rate you have a lot more "shopping" to do as the list of the countries is much larger: Ireland, Cyprus, Slovenia, Poland, Netherlands, Malta, Thailand...
All other countries (that have no DTT) fall into 30% tax (including UAE).
More details:
https://taxsummaries.pwc.com/united-states/corporate/withholding-taxes
So, if you have $2M in your stock portfolio and it produces you 4% - you would be making $80k/year and if you decide to live in Romania for eg, that would leave you with $72k after the WHT. That's $6k/month and more than enough for above the average lfie in Romania.
Edit:
Also, worth noting is that if you invest in Canadian or European stocks from UAE you'll pay 15% WHT on these. Even if you buy for eg. $BNS on NYSE you'll still pay 15% WHT (and not 30%) - so you don't have to move to Thailand LOL