Most Lords are tyrants who tax their nobles the maximum 50% that they are able and others are poor businessmen who tax their regions far below the threshold that can be supported. It's usually prudent to avoid those types of Lords regardless of the overall sizes of the estates they offer.
Unfortunately the current region information pages don't allow you to do so efficiently, as they show you the estate sizes and whether they are vacant but omit all other information. The only way you're able to see the Lord's tax rates is to travel to a particular region in order to check the estates in person through the "manage estates" page. This is a major hinderance since in order to make an informed decision using it you'd have to spend days travelling region to region, recording the information outside of BM so that you don't forget it and then, once it's all collected, spend some additional amount of time travelling to whichever region you decide on taking.
That is such a difficult feat that it's downright impractical and I doubt anyone ever attempts it. More likely the most anyone is willing to do is to flip through the region information pages in search of the largest estate in the wealthiest region, tax rates be damned. This rewards Lord's who are tyrants or poor businessmen because there's little anyone can do to keep from falling prey to them.
Hence why I'd like to see more in-depth region information pages which include tax rates.
