This is a broad question, and there's no one right answer. Different people have different preferences, and the various software packages available try to differentiate themselves by working in different ways.
If you have a Mac, GarageBand probably came with it. For many people it's good enough, and it's a solid introduction to the style of working used in Apple's more advanced Logic Pro.
There is much argument about what the PC equivalent of GarageBand is, Reaper being one candidate.
Cubase is the most famous of the traditional "piano roll" music production packages.
Ableton Live! has a somewhat different workflow, that some people prefer.
I want to give special mention to the "tracker" class of music software. This style of sample-sequencing software was popular on Amigas and other 16 bit platforms. OpenMPT one PC tracker app that's still being maintained.
Few of these applications are free (OpenMPT is) but most of them have crippled or time-limited demos, to see if they're worth your money.
The only answer is to try a few, and see what works for you.