Check-in on the kingdom chat and take note of the players you like and which allegiance banner they fall under. You can also look at different SOPs on the map to see which allegiances have claimed them if you're after a more powerful banner. Some banners may not be as powerful as others, but they may be nobler and kinder. You have to sort out which values are most important to you in an allegiance. That's how I would go about it, at least. I don't know of a database that holds info on the different banners. This is really something you learn best from playing and interacting often. I tried out a couple of different allegiances before I found one where I really feel like I fit in, and that may be something you experience too. As long as you don't jump around too often or reveal details from inside one allegiance to another, it should be all right.