I utterly hate trade leagues. I find, being a member totally useless. You have the same compete chance as the leading nation. Okay, but so does every other league nation has and there are many trade league nations. You can't even compete with the members and most of the time you have Modena, Ferarra or such nations blocking the CoT places, trading in other CoTs won't work too wel since they are mercantile and competing for spots in the home CoTs, yeah, have fun.
As a small nation, I usually take National Trade policy and Shrewd Commerce Practics as first 2 NIs. Play Switzerland or Holland, take those NIs and go fully Free Trade and noone of those stupid trade leagues will be able to throw out a merchant of yours, while they pay tons of gold to unsuccessfully place some merchants with Venice or Hansas compete chance on foreign CoTs which is rather bad.
Also, yes, the games I had always taken National Bank, I will now take Church Attendency. It'S nice to have stab cots significantly reduced (if you are not a trade nation of course, else you would take the trade NIs) and although I mint more than before, I will always have a spot left for a Master of Mint, as I don't tend to use advisors too often.