Reaper isn't too bad and i'd argue it gives Cubase, Pro Tools and Logic a run for their money. Some aspects of the UI are a little clunky but i think it's acceptable given cost and what you can achieve with it.
There's also Fruityloops, now rebranded as FL Studio, and it's what i started with when i was a kid. It has changed a lot over the years and you can accomplish a lot with it but it is pretty backwards in a lot of areas, routing or side-chaining for example, which made those learnt skills difficult to translate to other DAWs and to IRL studio setups.
I personally wouldn't recommend it especially given the cost but thought it's worth a mention if you're trialing stuff.
Pro Tools was always my go to for audio work (mostly because it is what i was taught throughout school and uni) with Ableton for any electronic/loop/plugin based projects as i found it's extremely versatile plus i could use MaxMSP from within. Biggest downsides of Ableton is audio editing side of it is a little pap compared to other DAWs (Cubase, Pro Tools etc) and now largely cost.
Edit - You also have Reason, The Prodigy were big users of it, but i never could get my head around it outside of the cool factor of patching synths and plugins etc.