It's really good to choose between an empty server and one where banner stacking is in right now.
It's not always empty. It's often empty, because there is still space in EU2, but if EU2 gets full, EU5 starts up and can then last a while. With banner balance on, there was always one of the clans abusing the banner balance on both servers, that's why EU5 was never empty. And yes, you HRE guys were the worst offenders, together with the Grey clan.
Before they turned off banner balance on EU5, there was no way to have a fair siege match as a random dude. All you could do was pick the banner of a clan, or be content with an average multiplier of below 2.