Fruity loops is great, since it comes with everything you need. Reason used to be another good choice but I haven't used it in many years.

The best advice I was given relating to this exact question (20 years ago) was to invest in a midi keyboard, stick with one piece of software and use my free time experimenting with it. That's it. Watching youtube videos is a complete waste of time in my opinion, since a lot of that crowd has fallen into the trap of reviewing one plugin after another, without really being able to create art. At best it's a circlejerk of mimicry and patterned-knowledge regurgitation.