Which is demanding testing courses now?

It depends on the type of testing you are going to perform:

For Automation - Selenium and UFT(QTP)

For Mobile Automation - Appium

For Performance - Jmeter and loadrunner

For Services testing - SOAP UI

For unit testing - mbunit, testng

Mobile QA

The development of mobile apps and games are emerging every day. The ERP and PLM domains are converting their Software Tool into Real-time usable applications on Mobile platforms.  

So the skill set to be capable of  testing Mobile Apps (UI, Functional, Non-Functional and Automation)

tech democrocy.its a demanding testing course.

Selenium for web testing and Appium for mobile testing

Software Testing as a complete technology -That has a really good scope only if it’s specialized - HP UFT, Selenium, Mobile, Android, iOS, Database, ETL, Performance 

Automation Testing Using selenium webdriver

Manual testing  using black , White and Gray Boxes techniques

The Automation testing using tools like QTP,Selenium,UFT and the cerification in ISTQB

The very demanding testing course these days is Selenium.

ISTQB is a demanding testing course and certificate

As per the demand Selenium automation testing and ETL Testing

Now a days, demand of a software or applications are increasing day by day. I would like to suggest to start with selenium as it will be easy to grasp being in testing.