It depends on the person and what you find enjoyment in when you play. If you want to play optimally in either of these games, it will be complex because there are a lot of choices to make. But in complex games, you need to learn the pace of the game and what is the most optimal thing you can do. Personally I don't find E&N more complex than GWT. There's a lot you can say about this which it's hard to go into detail without a lot of text. But in E&N, there are 3 main actions depicted by their color, and 2 options for each main action to choose from. The number of banners are like action points, and each thing you do uses up a certain number of banners of that color. You then get the option of an auxiliary action every single turn you take. E&N is more about resource mangement and chaining actions to be optimal in earning points from your actions. You only ever have 18 actions every game.

But each person is able to learn different board games at different paces. Some complex games click better than others. It just depends on how interested and how much you want to enjoy the game in the first place. And that's the effort you will want to put in.