Patience and try to pay off. After x experiments with cheap Noname and B-brands all of which turned out to be bad, I am now found it. A battery in original quality at an affordable price. I use 3 of Weiss EN-EL3e in my 90D and am also after 2 months still perfectly happy. The original batteries are definitely not better.The supplied protective cap is especially when traveling a nice plus for this battery. In half a year I will report back how the battery has beaten in the long-term test.
Eight months later - the beginning of March 2011: The EN-EL3e runs constantly and has passed the endurance test. So rule of thumb, the battery was determined around 300 hours of use.