I heard before that it is not easy to transfer an interview to a different consulate. I heard from two people whose requests were denied. But each case is different, and it doesn't mean they deny every request. As long as the conditions are met. Regarding where you can find which consulate is better, that information does not exist. Most consulates don't announce the dates they are interviewing, how many people are waiting in line, how fast they are processing, etc. So we don't know. One might transfer and end up in a line where things are worse. Who knows.