I have this one:
http://www.toysrus.com/product/index.jsp?productId=10860397
It was easy to install, padding is ok, it is starting to feel heavy now--he weighs 19lbs. It's rated for 30lbs and 30 inches. He's 29in. I am probably buying a new one today. It was top-rated when I bought it. I don't really have any complaints.