You should learn the both and eventually makes your choice, no crypto enthusiast should limit himself to only a particular aspect, you need some trading knowledge in making investment decisions, both type of trading all have different outcome and requirements. Particularly for a very busy person, long trading should be the best as you do not habw to watch the market all day while short trading requires constant monitoring
Actually, he should go learn how to trade first as he cannot make a decisions whether he wants to go long term or short term without learning. The shorter the term, the more the risks which is why a lot of people always end up preferring long term styles of trading, but the reality here is that, you cannot get the best from any style of trading if you do not even have the knowledge to pull through.
At the end, the OP will just have to find which one suits him best in the long run, and that decision cannot be made without having some good understanding of how all the style of trading should be and the strategies he can use to trade them effectively.