Three top

After a thorough examination I came to conclude that this three PTC sites are more to my liking, shown in no particular order :  

The simpliest PTC site and it pays well:

This one is more diverse, there is also offers, super offers, games:

This one is also more diversified, there is also offers and there is an option of downloading a small program which includes a banner on the top of your desktop, and counter.The time you are active on the desktop is counted as points which are than transformed in dollars: