Personally, I prefer the Masala Chai, because it's got more spices (and thus more flavour). However, I did just have a cup of the Chocolate Chai this evening, and I found that 3 level teaspoons and filling my ingenuiTea up partway through the big writing (maybe a cup and a half?) and steeping for about 6 minutes or so, yielded a decent cup of chai.
A few other things I've discovered...Right when you pour the water on the tea leaves, put the milk straight into your mug, put your sweetening in the mug as well. When you pour the chai into your mug, do it in parts (thirds works well for me). Each time, stir your milk/sweetening/chai mixture. This way, the sweetening will be evenly distributed, and your tea a little stronger, because each part was in direct contact with the tea leaves for a bit.
If that's not strong enough, leave a little bit of the water in the bottom to steep, and your next cup will be quite strong!
Anyway, I hope this helps!