I have been working with Sibelius (the typesetting software) for over twenty years, since the first version for PC. Prior to that it was available only for the Acorn computer (I know, niche!) so the eventual move to a more widespread platform was the beginning of a compositional revolution, no less.
Before buying my own copy I used to nip along to the British Music Information Centre, which has since morphed into something different, where one could book a computer and settle down for an afternoon and tap in what had formerly existed only on paper. Then, towards the end of 1999, I received a commission for a piece that had a deadline so tight that there was simply no way I was going to be able to complete it without Sib, so I spent the down payment for the work on my own copy of the software.
It was expensive back then, around the £700 mark if I remember correctly, but it was undeniably an investment, and I have been typesetting with Sibelius and writing with it ever since. Given the time, space and opportunity I would always rather do my preliminary scribbling with paper and pencil, but for the final product I would never now submit something hand written.
Sibelius also brought publishing into the hands of the writer, and I have always preferred to control my own content and be in charge of its own destiny, something that is only tangentially connected to the fact that my pieces that are with publishers have earned me (as opposed to them) a big fat zero over the years. Thus my preference for making my scores free to download and distribute and, therefore, easier to perform, while retaining all the other rights.
Sibelius was eventually bought by Avid who upgraded it a little and then booted out the original development team, while that initial Sib team have gone on to develop Dorico, but this will need to be a significant improvement on what I already have to make me consider switching. I was reminded of this yesterday when I accidentally clicked on the wrong button and discovered a feature I had been yearning for for years, so who knows what else is still ticked away in my current version of Sib to make it even more useful in the future?