It depends on what you want to do with them and your personal properties. For me the first one would be the easiest. A fugue is a bit far fetched for a beginner, whatever the key.
If a beginner is prepared to take it slow and work carefully, he can definitely learn the first two. They are musically quite simple. Time signatures and keys with many sharps and flats are not difficult to play physically (for an adult with good size hands), the difficulties are more of the mental kind, so whether you struggle or not depends on how easy it is for you to grasp such things and how easy it is for you to memorize.
But does it make sense? To learn something that maybe has little musical value just because you want to start on a certain scale supposedly recommended by someone who lived 200 years ago and in a very different world? While there's so much material for us now to start on? Besides old Fred was known to never teach beginners, so what he recommended may have worked better when learning better physical technique as someone already quite familiar with the piano.
OTOH I also see a problem with the common approach of waiting so long before adding more keys. It's much harder to think of the whites and blacks as equal keys (which they are when we study music theory) when the blacks are so rarely used in the first years. I would see some value in an approach where the whole keyboard is used as soon as possible, but that may be because I am a very "holistic" type of a learner. Learning small bits and pieces and then glueing them together has never worked for me. I need to "get the big picture" first and then add details.