It depends. I used iMovie for simple stuff back in the day when Arata Academy’s YouTube channel was launched (before 2011). It was a great way to start due to its practicality, but while I was making some progress in video editing, iMovie became a little bit stale for me. I didn’t enjoy constantly importing videos to the Library and a lot of times iMovie ends up rejecting some sources. It forces you to follow a certain Apple way and it lacks creativity. But it is a very good program to start with.
Between 2011 and 2012, I used Screenflow a lot for editing because it is a quick and very simple program.
In 2013, I started using the Adobe package (Premiere and After Effects).
The reason I’m telling you all this is to illustrate the following: if you’re starting now, it is not imperative (or financially viable) to have the most complex software. To speak the truth, that can even be counter-productive. Start REALLY SIMPLE and evolve with time and experience. Software does not make miracles, it is just a tool. You should be the one doing the art.