I use Cubase. Like you it was bundled years ago with an interface and I learned how it works (for the most part) and stuck with it. I had an aversion to Protools because at the time and really still is in many ways expensive and proprietary. I started to to mess with Ableton, but didn’t always like the way it could push my music into the looping arena. I really try to avoid the repeated loop based music of today with canned samples, etc.. It is a good platform to access virtual instruments and honestly have been meaning to install it on my new system and give it a go again.
In a totally different way I have been using Roland Zenbeats solely on my iPad. The irony is it’s basically an Ableton style system that’s probably even more dependent on loops and samples. I use it a bit differently (I used Ableton this way too) to quickly get some drum beats down and quick ideas while relaxing or to just jam over, but then would start anything serious in Cubase.
I used Reaper when it first came out and was totally freeware. It obviously has caught on, but at the time I didn’t want to get wrapped up in something that might disappear or have proper support. I had paid for Cubase and wasn’t going to just waste that investment. Now that PC’s have reached the level where memory and CPU are not an issue most all DAWs are good and are stable on a properly configured system. It seems like whatever people started with they stay with or if they’re in the industry then Protools is it.
I forgot to add that Cubase comes with some of the best virtual instrument platforms and drum making tools around. It actually is packed with a lot of useful stuff. So much that I can’t keep up with it all sometimes.