Hello Gajan!
Thanks for your reply! I have read the forum a little and have come to the conclusion that it may be better to stick with Delta, as I normally book inexpensive Economy tickets. I am still frustrated that Delta basically abolished the possibility to book hotels through them, as we have been able to get good deals for our miles there several times. They also had a huge choice of hotels and lots of available dates and a comfortable website.
It seems the airlines' battle against their FF customers continues - well, at least with Delta it seems I can actually collect some miles, and if the stars align right, I might be able to book an award ticket every other year or so...